Move HeliCrash and CarePackage area variables to markers

This allows finer grained control of crashsite, carepackage and infected
camp spawn positions and radii (further north, south, east, west, etc.).

Also removed some hardcoded checks for Chernarus, since
dayz_townGenerator should always be off on other maps for now. Someone
may add town generator coordinates for other maps later.

Related vanilla commits:

b20b402bf0

7c8b69eb82

7dfd3ef9cf

SQF/dayz_code/system/antihack.sqf

@@ -9,7 +9,7 @@ inGameUISetEventHandler ["Action","false"];
 // thanks to Tansien the great
 // run only once per character life
 {
-	_plant = _x createVehicleLocal dayz_centerMarker;
+	_plant = _x createVehicleLocal (getMarkerPos "center");
 	uiSleep 0.1;
 	if (sizeOf _x == 0) exitWith { 
 		PVDZ_sec_atp = toArray ("Plants texture hack for type " + _x);