func_groupcount.c: Adding Group Variables + additional Group functions

[intellasoft]

DumpGroups

• New application. This will dump all channel group membership and associated
  variables

Groups and Group Variables

• Group variables can be set on a group once the group is created
  When a group is destroyed, all variables on that group are also destroyed

  A group variable is somewhat like a global variable, but it's on a per-group
  basis.

  GroupSet - Adds functionality to the manager to be able to set a GROUP()
  on a channel.
  GroupsShowChannels - Show each channel and it's associated groups
  (a channel will be repeated for each group@category
  it's a member of)
  GroupsShowVariables - Show variables in each group@category, one event per
  group, all variables are contained in each
  group@category event
  GroupVarSet - Set a group variable (the group must already exist)
  GroupVarGet - Get a group variable

• New Manager events:

  GroupCreate - Event is fired any time a group is made,
  ie: Set(GROUP=x) or Set(GROUP()=x@y).
  This event is only sent on when a channel is added to a group
  that did not exist previously.
  GroupChannelAdd - Event is fired any time a channel is added to a group
  GroupChannelRemove - Event is fired any time a channel is removed from a
  group
  GroupDestroy - Event is fired when there are no longer any channels assigned
  to the group
  GroupVarSet - Event is fired when any group variable is changed

• New CLI Command

  group show variables

• New Application

  DumpGroups() - Show groups and group assigments (similar to DumpChan)

Resolves: #291

[asterisk-org-access-app]

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The currently active branches are now 18, 20, 21 and master.

[InterLinked1]

cherry-pick-to: 18
cherry-pick-to: 20
cherry-pick-to: 21

[InterLinked1]

See inline comment:

[kobaz]

Whoops. I just realized my push was the same code. I forgot to 'git add'. This one should be all set.

[kobaz]

multiple-commits: interim