Registers an event handler for a specific CBA event.
| _eventName | Type of event to handle. STRING |
| _eventFunc | Function to call when event is raised. <CODE> |
| _eventId | Unique ID of the event handler (can be used with CBA_fnc_removeEventHandler). |
_id = ["test", {systemChat str _this}] call CBA_fnc_addEventHandler;Spooner, commy2