GS: Charge 5000 opcodes to call ScriptTown::FoundTown

This call is very expensive and calling it in a loop when it fails
can consume all available CPU time

Add a further 50000 charge if a town name cannot be generated

src/script/api/script_controller.hpp

@@ -126,6 +126,11 @@ public:
 	 */
 	static int GetOpsTillSuspend();
 
+	/**
+	 * Decrease the number of operations the script can execute before being suspended.
+	 */
+	static void DecreaseOps(int amount);
+
 	/**
 	 * Get the value of one of your settings you set via info.nut.
 	 * @param name The name of the setting.