split belle_sip_snprintf in 2 functions (belle_sip_snprintf and belle_sip_snprintf_valist) to enable usage with a va_list too
improve refresher behvior when pending transaction need to be canceled
avoid transactions to be refreshed in various case where they must be stopped
resolver should work even if no /etc/hosts
on ios, start background task during network-critical operations of the channel.
fix bug in refresher, it shall not consider only 200 but 200..299 response codes
take a background task when notifying incoming messages also
Merge remote-tracking branch 'linphone/master'