Disable TownGenerator and plant spawner by default

Junk and plant spawning is disabled by default. It can be enabled via
dayz_townGenerator config variable and positions blacklist (for trader
cities, etc.).

The trader objects spawn code was consolidated to functions.

SQF/dayz_code/compile/local_spawnTraderCities.sqf

@@ -0,0 +1,25 @@
+private ["_fires","_object","_type"];
+
+_fires = [
+	"Base_Fire_DZ",
+	"flamable_DZ",
+	"Land_Camp_Fire_DZ",
+	"Land_Campfire",
+	"Land_Campfire_burning",
+	"Land_Fire",
+	"Land_Fire_burning",
+	"Land_Fire_DZ",
+	"Land_Fire_barrel",
+	"Land_Fire_barrel_burning",
+	"Misc_TyreHeap"
+];
+
+{
+	_type = _x select 0;
+	_object = _type createVehicleLocal (_x select 1);
+	_object setDir (_x select 2);
+	_object setPos (_x select 1);
+	_object allowDamage false;
+	if !(_type in _fires) then {_object enableSimulation false;};
+	_object setVariable ["", true]; // stops global setVariable by sched_townGenerator
+} count _this;