That prevented from building the SDK with other version of libxerces
than 3.1, which may happen while building Flexisip since it uses
the libxerces provided by the system.

Additionnaly, this commit bring some cosmetic changes:
* Usage of « foreach » syntax.
* Usage of automatic types.
* Usage of '==' operator instead of string::compare() method.

Previously, on the call of getOrCreateBasicChatRoom, a chat room with the same peer address was returned without takking account of the local address that could come from multi-accounts.

Default proxy could be different from the URI we want that lead to unexpected behaviour on wrong assertion.
Update subscription on remote conference list event if it was the same as the cleared proxy config.

From https://docs.microsoft.com/en-us/xamarin/ios/internals/limitations#reverse-callbacks

* You must flag all of your callback methods with the MonoPInvokeCallbackAttribute
* The methods have to be static methods, there is no support for instance methods.

-change behavior in case of network switch in call state outgoinginit. New behavior is to initiate a new invite with replace header with call-id, from-tag set while to-tag is set to 0. Server UA receiving this new invite tries to found the original dialog and continue the Linphone Call if possible. Replaced call is declined with a 603

This reverts commit 8eb34e63.

Split capability negotiation, single call, secure group chat, message, ephemeral message and audio video conference test suites

Create a new reason : Transferred.
Propagate user reason to call session.
Play ring tone only if tone indications are enabled.

Tester : Link tester to OpenLDAP and enable debug logging on OpenLDAP.

Use call State when streaming/Paused/PausedByRemote in tonemanager to avoid to loose state connection when playing tone.
Play error tone only if tone indications are enabled.

Synchronyze tonemanager with DTMF callback and on chaing state like Paused/Streaming running to continue ringing if needed.