(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

functions.h

@@ -266,4 +266,7 @@ void DeterminePaths(void);
 char * CDECL str_fmt(const char *str, ...);
 
 void bubblesort(void *base, size_t nmemb, size_t size, int(*compar)(const void *, const void *));
+bool CreateOTTDThread(void *func, void *param);
+void CloseOTTDThread(void);
+void JoinOTTDThread(void);
 #endif /* FUNCTIONS_H */