- Update to 4.0.0:
* modify configuration APIs to use eXosip_set_option
* fix bug: do not create new PRACK if it already exist for an answer.
* use ephemaral port in standard TCP and TLS version.
* return tid number so that we can match the response event.
* use system independant time for osip_gettimeofday on unix platform.
* major API update: several "struct eXosip_t" can be
handled at the same time. This can be used to have several
transport layer running at the same time.
* many tiny other change. (forwarded request 180741 from Fisiu)