add new parameter to refresher's listener to indicate if the refresher is going to retry the request.

This reverts commit d90ee741.

Revert " add support for header Accept"
This reverts commit fbb27d34 and 895578bb

-add max-forward to ack sent by ict

enhance nat helper mechanism so that even unchallenged requests can be immediately resubmitted by the refresher if the contact could not be properly set the first time.

 - 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.

* fix many bugs and crashes:
  - rport shall not be set if not present in the request
  - received shall not be set if identical to via's host
  - belle_sip_response_get_return_hop() wasn't working without received parameter
  - belle_sip_response_get_return_hop() wasn't working if no rport and no port (that is default port to be used).

fix param less address spec (I.E header like From: sip:toto@titi.com:tag=asdad )