freetdm: ftmod_r2 - set feature FTDM_CHANNEL_FEATURE_IO_STATS just when the channel is in FTDM_CHANNEL_STATE_UP state

freetdm: ftmod_r2 - replaced deprecated ftdm_r2_configure_span() by ftdm_r2_configure_span_signaling(), all r2 default params now stays on ftmod_r2

         poll_events pointer, enabling/disabling channel reading flag when needed.
		 also removed the test for FTDM_CHANNEL_OPEN flag on ftdm_channel_wait().

freetdm: now wanpipe_channel_next_event() doesn't expect the flag FTDM_CHANNEL_EVENT to be set. If it is, it just clears it. Also removed unused code from wanpipe_channel_next_event()

freetdm: ftdm_channel_read_event() to retrieve events from a channel, removed from ftmod_r2: ftdm_r2_sig_read(), FTDM_R2_PROCESSING flag and locks for ftdmchan

freetdm: made ftmod_r2 use FTDM_SPAN_USE_SIGNALS_QUEUE and properly send FTDM_SIGEVENT_SIGSTATUS_CHANGED

         if this parameter is set to 0 ftmod_analog will not wait
	 for dial tone before dialing out the requested number.
	 Anything bigger than 0 is the units in milliseconds to
	 wait for dialtone before aborting the call.

apparently some sip device vendors did not read the RFC (who knew?) adding verbose_sdp=true var to add needless a= lines for standard iana codecs that explicitly do not require them