Enhancement: dialogModesToolsInit should check if function entry is valid

[Adanteh]

Right now if you leave the function class entry exist like

			class Events {
				class OnInit { };
			};

then you'll get an error that just shows up as ERROR: 'call ' in Arma, which makes it pretty hard to figure out what you're doing wrong. Would be nice if you could add if (_function != "") before the call.

[zgmrvn]

i'll go with something like :
if (_function == "") exitWith { ["%1 : empty function for %2 event", _module, _event] call BIS_fnc_error };