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.

	* Replace ftdm_channel_flag_t with defines. We reached the 32bit limit where does not seem reliable
          to keep using enum.
	* Flags member for ftdm_channel_t is now uint64_t
	* Added FTDM_CHANNEL_CALL_STARTED flag to indicate when the API user knows about a call
	* Refactored raw_data member for ftdm_sigmsg_t. If raw_data needs to be freed it must be requested explicitly
          through the autofree member
	* Added collected member to ftdm_sigmsg_t for FTDM_SIGEVENT_COLLECTED data instead of using raw_data
	* Created define FTDM_DIGITS_LIMIT for DNIS/ANI digits limit
	* Fix some stat checks and outdated code in ftmod_analog
	* Refactored ftdm_channel_get_history_str API to return the time offsets and time since last state change
	* Do not send FTDM_SIGEVENT_STOP and FTDM_SIGEVENT_RELEASED on calls that were never reported to the user