GitLab

 - 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.

clean input stream parser (no more goto, no more recursion)

- connection fallback mechanism in progress.

allow transaction to kill dead channels in case of timeout

Fix channel retry mechanism by using linked list of addrinfo structures instead of a belle_sip_list_t for DNS A and AAAA results.

optimize to_string mechanism.