(svn r2391) - Feature: saving games happen in a seperate thread so you no longer will have to wait such a long time (especially handy on bigger maps and multiplayer games). The mouse also changes into the 'ZZZ' state :P. The thread on windows is currently given a little-bit-less-than-normal priority so it should not interfere that much with the gameplay; it will take a bit longer though. Upon the exit of the game any pending saves are waited upon.

- Fix: fixed GetSavegameFormat() so that it takes the best compressor (highest), or a forced one added with the parameter
- Open issues: 
1. Don't attempt to load a game while saving is in progress, it will kick you back to the intro-screen with only the vast ocean to look at.
2. The server is disabled from threaded-saving, but might be enabled in the future.
3. Current implementation only allows 1 additional running thread.
4. Stupid global variables.....grrr
Big thanks for TrueLight and the amazing memorypool :D

win32.c

@@ -2242,3 +2242,26 @@ bool InsertTextBufferClipboard(Textbuf *tb)
 	}
 	return false;
 }
+
+static HANDLE hThread;
+
+bool CreateOTTDThread(void *func, void *param)
+{
+	DWORD dwThreadId;
+	hThread = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)func, param, 0, &dwThreadId);
+	SetThreadPriority(hThread, THREAD_PRIORITY_BELOW_NORMAL);
+
+	return (hThread == NULL) ? false : true;
+}
+
+void CloseOTTDThread(void)
+{
+	if (!CloseHandle(hThread)) DEBUG(misc, 0) ("Failed to close thread?...");
+}
+
+void JoinOTTDThread(void)
+{
+	if (hThread == NULL) return;
+
+	WaitForSingleObject(hThread, INFINITE);
+}