set idle pattern to 255 instead of 0 to prevent clipping sound on short frames from mod_native_file FS-2772

freeswitch.spec moved to support freetdm instead of openzap including hooks to compile with libsng_isdn and wanpipe. Added mod_silk, mod_codec2 mod_cidlookup, mod_mp4v. Added runtime requirements and build dependencies. This one is a major change

mod_sangoma_codec: do not return 0 len frames and return silence instead when there is no transcoding output
                   update stats only when we really receive a frame

watchdog_step_timeout watchdog_event_timeout (milliseconds) to detect a problem in sofia and shutdown instantly