linphonecore.c: linphone_core_redirect_call should interpret url as linphone_core_transfer_call does

remove deprecation of LinphoneChatMessageStateCb, since it is already marked as deprecated in all functions using it.
fix a few warnings

remove linphone_core_create_default_call_parameters() because this function is dangerous and error prone.
Indeed, it cannot guarantee that the created call params are compatible with the call being accepted or updated.
For doing an outgoing call there is no problem in using it but linphone_core_create_call_params() is better and hard to mis-use.

fix multiple memory leaks, mainly in gtk UI

gtk: implement fullscreen video mode by having gtk managing the video window (not created by mediastreamer2).

add linphone core api and setting to allow forcing the video capture size, and take a snapshot of preview during calls.