- Manually merging latest code from gideon.gsm branch after review/inspection/modifications

fix vs2008 pro project dependency for mod_gsmopen - if anyone wants the solution files for express and wants to help please open a Jira with a patch and I will review it.

freetdm: refactor ftmod_gsm.c code to use proper core functions and interrupts to wait for io and state changes

         - Add definition of FTDM_MAX_SIG_PARAMETERS to have a standard limit for signaling module parameters

FS-4177 play-file-done was not previously possible it was part of supressing play-file, try this patch