when initiating a call;
- from header
- account
These 2 parameters are dependent from each other which makes tricky for
the core to know exactly which account to use and the correct from
address.
In most scenarios, the from address is the account's identity address
but it is not always the case such as in the case of a direct call.
Moreover, the account cannot be always deduced in a straightforward
matter such as if the core has no default account (but it is registered
with one or more accounts) and the call parameters have not set one.

The algorithm for choosing an account is the following:
1) search in the call parameters
2) get the default account
3) look up for the best guessed account based on the from (if known) or
   to address

The algorithm for known the from address is the following:
1) look for the from header in the call parameters
2) look up for the identity address of the account (if known)
3) get the core primary account

Set Ik SDP attribute based on the account used for a call

Use account set in the call parameters before retrieving the NAT policy.
It may happen that a call session is buuild without passing an account
and in such a case, the SDK will do its best to get one

It allows the organizer to choose whether participant are speakers or
listener in a conference.
For scheduled conferences, if a participant is not in the list of
allowed participants, he/she will have its role set to listener (i.e
audio stream will be sendonly from the server side and recvonly on the
client side).

Non scheduled conferences will have the organizer and participants to be
speakers.

The dynamic change of a participant role is not supported yet once the
conference is started but it may be done prior to it by updating the
conference informations

- a RecvOnly audio stream with content DTX and the participant label for each participant of the conference. A secured conference will have N audio streams (1 sendrecv for the local participant and N-1 recvonly for the other participants)
- add security level to the conference parameters
- pass security level information to the conference server
- add encryption information to the database table storing conferences
- pass security level down to MSAudioConference and MSVideoConference objects
- add extra video stream for encrypted conference in active speaker layout

if possible.
If a core supports IPv6 and IPv4 addresses, the answered will look at
the offerer IP address family and it will set a media server with either
IPv6 or IPv4 address depending on the offerer choice.

- Delete classes IdentityAddress and ConferenceAddress
- Make Address a derived class of HybridObject
- Use smart pointer for objects of Address type whenever they need to be handled by the applications

Add property to disable deletion of empty chatrooms
Enable compiler option '-Wunused-parameter'
Fixed possible null pointer exception in Java wrapper for Android
Update copyright notice in wrapper files

Handle dial out conference while there is already an ongoing conference:
- the conference server will always initiate call in dial out conferences if there is no one yet established
- clients that are already in a conference call will reject any new incoming call from the same conference server with a 486 Busy Here

If a participant requests a video stream of another participant whose video direction is inactive or recvonly, then the conference server will reply with an inactive stream
Remove label and ssrc from participants whose video is disabled
Do not send separate notifys for changes of an ssrc and media capability or availability changes

Various fixes and improvements of the video conferencing logic for "active speaker" mode, in order to avoid situations where a black screen video is sent while it should not.

Fix issue where the video conference mixer does not output video when there are two participants only in the conference.

If the client receives a partial notify for an unknown participant device, then he will send a subscribe to the server to clear things up

Improve tests:
- verify behaviour when participants are added in a quick succession to remote conference
- improve chat room test coverage

Rework send invitation API: do not give chat room params but a boolean stating whether the chat room should be encrypted or not

Add ICS cancel/update capability.
-> Update: participants already invited receive an ICS with the same UID and the sequence incremented by one when the information up to date
-> Cancel: participants that are no longer part of the conference, receive such ICS

In order to globally cancel a conference, an admin can send an INVITE to the conference with an empty list of participants

time SDP field (t=) is used to know whether the INVITE isaiming at joining a conference or update it:
- if t=0 0, the client wishes to join a conference
- if t!=0 0, the client wishes to update the informations of a conference (subject, start time, duration, participants)

This saves time to establish the audio stream.
Starting before ICE verified was not a good idea: it will trigger retransmissions, and retransmission interval growing over time makes the handshake slower.
Also, fix an issue where callee sets host candidates as default candidates in SDP, sflrx must be preferred.

Implement audio video conferencing dial-out if conference must immediately start (start time in SDP is 0)
- the body of the INVITE sent out by the server has three parts:
  - SDP
  - resource list with the list of participants
  - SIP frag with the organizer of the conference

Move resource list and sip frag parsing function to the factory

Always clear devices when destroying participant

Change RTP port range of lise_rc

Do not move from transition call state (Updating, Pausing, Resuming) if there are updates yet to be accepted

Set participant device state to Left when receiving a NOTIFY to inform the core that he/she has definitiely left the conference

Improve conference documentation:
- linphone_conference_get_participant_list and linphone_conference_get_participants do not include the local participant (me)
- linphone_conference_get_me() returns the local participant

Modify tests runnign local conference hosted on a device to create them on a server
Fix do not add rtcp-xr line if it is disabled by the core

If a participant has video capabilities enabled, he/she will only be able to toggle its own video and keep seeing the one of the other participants

- clients send a reINVITE with the desired stream based on their choice of layout upon reception of:
  - full notify state
  - participant added
  - participant removed
- change of layout (via conference params update or setLayout method) triggers a reINVITE from the client with the new desired streams
- server sends reINVITEs to clients only to notify them that they joined a conference. If the client calls a conference URI, no reINVITE from the server is sent

Add conference available media changed callback
Conference layout renaming: None -> Legacy
Add linphone_core_create_conference_params_2 in order to create conference parameters from an existing set
Split local conference tester to speed up test run
Rename testers Audio Conference (Basic) -> Audio Video Conference (Basic) and Audio Conference (Advanced) -> Audio Conference
Add media direction to string function

The conference server tries to add them as soon as possible (i.e. in the IncomingReceived call state). At this stage the participant device is in state ScheduledForJoining.
Once the call reaches the StreamsRunning state, the participant device state will move to Joining is ICE is disable. Otherwise, the server will wait for the ICE reINVITE before changing the participant state.
The server also sends out an update in order to offer the right streams based on the chosen layout.
The participant device state will ultimately move to Present once the client accepted the server offer and the other participant are notified of the addition of the participant device.

- participant added to conference -> onParticipantAdded
- participant removed from conference -> onParticipantRemoved
- participant device added to conference -> onParticipantDeviceAdded
- participant device removed from conference -> onParticipantDeviceRemoved
- participant temporarely leavy conference -> onParticipantLeft
- participant rejoins conference -> onParticipantJoined

Verify behaviour when a participant removes video from a video conference

- allow remote to schedule a conference on a server
- start and end time are passed as the values of the active time attribute in the SDP invite
- an ICS is sent to all participants to be able to join the conference by dialling the focus address

- create video stream to send and receive participant minatures
- add support for multiple video stream in SDP
- add label to stream to allow unique link between it and each participant in a conference

Correctly set stream direction in NOTIFY based on information gathered from SDP only
Deny subscription if conference event package is disabled
Clean up of main-db.cpp

Compatibility with Avaya and FreeSwitch servers:
- call is paused when receiving a response with all streams having RTP port set to 0
- add support for 100rel support/require level

Add SalStreamConfiguration class to represent the actual and potential configuration to be offered and/or accepted in the SDP

Rewrite offer answer engine, SAL stream and media descriptions and SDP to media description with C++ 14 constructs