GitLab

* fix crash when receiving a NOTIFY after a SUBSCRIBE is terminated

Conflicts:
	sal_op_message.c

Remove useless minutes_away and contact parameters to the linphone_core_set_presence_model() function.

Remove linphone_friend_set_presence_model() and make linphone_friend_get_presence_model() return a const pointer because the user should not be able to change his friends' presence.

Do not check equality of presence statuses because it does not work if the presence model of linphone core has been changed instead of a new one created.