Codechange: Use platform independent C++11 function for sleeping on a thread.

src/thread.h

@@ -20,6 +20,15 @@
 class OTTDThreadExitSignal { };
 
 
+/**
+ * Sleep on the current thread for a defined time.
+ * @param milliseconds Time to sleep for in milliseconds.
+ */
+inline void CSleep(int milliseconds)
+{
+	std::this_thread::sleep_for(std::chrono::milliseconds(milliseconds));
+}
+
 /**
  * Get number of processor cores in the system, including HyperThreading or similar.
  * @return Total number of processor cores.