add new function to check when messages need parsing to improve performance on parsing messages during originate

don't parse events for b legs from a leg thread in case they are using a monolothic python script as a group_confirm exec over socket to send it messages while the call is ringing

mod_callcenter: Add new eventsocket agent-offering.  Plus some documentation and better handeling of bad agent type -- FS-2869

gsmopen: retry serial initialization if failed, zeroing audio buffers, slower retry on soundcard busy (EAGAIN)

         this should fix potential call_data pointer corruption

         this fixes a race where the call is hangup even before the state
         DIALING is processed and therefore the HANGUP state change is
         ignored.

add presence-probe-on-register sofia param to send a probe on register instead of presence to deal with some broken phones and add some general improvements to allow multi homed presence

                        have been cleared. This should fix issues with
                        state transitions being ignored.

FS-535:  fix issue in is_lan_addr where 172.2 would match 172.250.x.x which is not RFC1918 this also fixes an chicken egg issue