Add group system

Initial commit, not tested in multiplayer yet. Some revisions still left
to do.

SQF/dayz_code/groups/joinGroup.sqf

@@ -0,0 +1,32 @@
+private ["_inviter","_inviterUID","_oldGroup","_uid"];
+
+_inviterUID = "0";
+_uid = getPlayerUID player;
+
+//Remove all invites to this player since they joined a group
+{
+	if (_uid == _x select 1) then {
+		_inviterUID = _x select 0; //Take most recent invite
+		dayz_activeInvites set [_forEachIndex,"delete"];
+	};
+} forEach dayz_activeInvites;
+dayz_activeInvites = dayz_activeInvites - ["delete"];
+
+//Sync change to all remote machines (less data than sending whole array)
+PVDZ_groupInvite = [false,_uid];
+publicVariableServer "PVDZ_groupInvite";
+
+_inviter = _inviterUID call dayz_getPlayer;
+
+if (!isNull _inviter) then {
+	_oldGroup = group player;
+	[player] join (group _inviter);
+	if (count (units _oldGroup) == 0) then {deleteGroup _oldGroup;};
+	
+	// Update saved group in DB
+	PVDZ_Server_UpdateGroup = [1,player];
+	publicVariableServer "PVDZ_Server_UpdateGroup";
+} else {
+	_this ctrlShow false;
+	systemChat localize "STR_EPOCH_INVITE_EXPIRED";
+};