GitLab

better management of partial SIP message

- always send expires according to the original requirement (unless a 423 is replied by the server)
- schedule a refresh according to the expires provided in the server's response

 - Use size_t instead of unsigned int for offset.
 - Add function to enable marshal check at runtime.
 - Enable marshal check in unit tests.

 - Use our own implementation of snprintf() called belle_sip_snprintf() to handle the various native implementations whose return values are not consistent.
 - Simplify error handling in marshalling.