====== adv.newGroupLink() ======
wrtc.adv.newGroupLink() is used to generate group call invitation links.

It generates and returns a unique group call link or address.

===== Arguments =====
wrtc.adv.newGroupLink(link, gid)
  * link - (optional) true: (default) return full link, false: return just address
  * gid - (optional) string containing group ID to use instead of generating a new one

===== Returns =====
A unique group call link or address.

There are checksums to make sure users can't fake group call links.

===== Example =====
**wrtc.adv.newGroupLink() may return:**
  https://webclient.com/?call=conf_groupcall@webclient.com;gc_gid=656982117;gid=AkvVWhVW1XJ4zeIjfoOH
There:
  * webclient.com is the address to the IXNX server
  * conf_groupcall@webclient.com is the address to the voice bridge on that IXNX server
  * gc_gid=656982117 is the ID number to the voice bridge
  * gid=AkvVWhVW1XJ4zeIjfoOH is the group ID

**wrtc.adv.newGroupLink(false) may return:**
  conf_groupcall@webrtc-beta.ingate.com;gc_gid=1557990253;gid=7BQ18Lf92zOU_C1qdMlL
There:
  * conf_groupcall@webclient.com is the address to the voice bridge on that IXNX server
  * gc_gid=656982117 is the ID number to the voice bridge
  * gid=AkvVWhVW1XJ4zeIjfoOH is the group ID

**wrtc.adv.newGroupLink(true, wrtc.adv.groupID) may return:**
  https://webclient.com/?call=conf_groupcall@webclient.com;gc_gid=656982117;gid=AkvVWhVW1XJ4zeIjfoOH
Instead of generating a new group ID this will generate a link that can be used to join the group call currently in progress. Send the generated URL link to someone you want to join the current group call. If they click on it they will join the group call.