freetdm: ftmod_r2 - use openr2 API extension to properly report incoming restricted ANI and restrict ANI on outgoing calls

change switch_strip_spaces to specify if you want it to dup the string or destroy the current buffer

         Added new channel command FTDM_COMMAND_SET_POLARITY
         ftmod_wanpipe - Added support to enqueue polarity events on FXO lines
	 ftmod_wanpipe - Added support to set polarity on FXS lines
	 ftmod_analog - Added support to answer and hangup FXO lines on polarity reverse
	 ftmod_analog - Added support to reverse polarity in the FXS line on answer and hangup
	 mod_freetdm - Added parameters answer-on-polarity, hangup-on-polarity and polarity-delay
                       to enable those analog features

         ftmod_r2 - updated api help and removed references to threads per channel,
                    not used anymore

mod_conference: Add XML output for conference run time, recording status and member mute-detect. Also add events for recording start and stop.

This work was funded by Xpander Communications.