Merge pull request #1196 in FS/freeswitch from ~PECHEN/freeswitch:feature/FS-10061-send-custom-variables-on-incoming to master

* commit 'ccae1567':
  FS-10061 [mod_verto] now it sends custom variables on incoming call via verto

FS-10091: [mod_conference] Conference play file with full-screen=true has side effect on member video

FS-10091: [mod_conference] Conference play file with full-screen=true has side effect on member video #resolve

FS-10067: [mod_sofia] add update-refresher profile param and sip_update_refresher channel var to use update for session timers

FS-10079: [mod_conference] Possible lockup when sending many commands to conference at once #resolve

FS-10036: update cJSON code to pre 1.4.0 release of cJSON.  this includes backports of all our fixes, and our build macros for windows and visibility.  It also makes it easy to drop in a new version, and to in the future be able to switch to a system version of cJSON easily (after all these updates are in, probably around v2.0 timeframe.  Note this new version adds a lot of extra error checking, fixes some buffer overruns, and improves parser and printer performance