FS-2989: Places ;fs_path= within the contact string <...> when using NDLB-connectile-dysfunction-2.0, instead of just appending to the end of the contact string.

         - MFC-R2 requires tone signaling that gets screwed sometimes
           if the EC is enabled during call setup.
         - EC is now enabled only when switching to a state requiring
         media (UP and PROGRESS_MEDIA)
         - The logic is aware of EC persist option in Wanpipe
         - Improved logging in ftmod_wanpipe to print EC state on startup

The defaults for these keys are empty.  This change allows them to be
set empty in the XML config without error.

         - Clean up ftdm_channel_set_sig_status locking and sanity checks
         - Set FTDM_CHANNEL_SUSPENDED when delivering FTDM_SIGEVENT_SIGSTATUS changed to SUSPENDED
         - Clear FTDM_CHANNEL_SUSPENDED when delivering FTDM_SIGEVENT_SIGSTATUS changed to UP
         - Update ftmod_r2 to honor local suspend requests when returning from alarm state

fix session timer failure when freeswitch is generating the sdp and there are enough dynamic codecs enabled to conflict with the 2833 pt (4 by default)

Prior to this change, calling flush_inbound_reg with @domain will
reboot all matching devices (if reboot is specified), but will not
actually flush the matching registrations.