(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

unix.c

@@ -11,6 +11,7 @@
 #include <time.h>
 #include <pwd.h>
 #include <signal.h>
+#include <pthread.h>
 
 #if (defined(_POSIX_VERSION) && _POSIX_VERSION >= 200112L) || defined(__GLIBC__)
 	#define HAS_STATVFS
@@ -554,3 +555,18 @@ bool InsertTextBufferClipboard(Textbuf *tb)
 {
 	return false;
 }
+
+static pthread_t thread1 = 0;
+bool CreateOTTDThread(void *func, void *param)
+{
+	return (pthread_create(&thread1, NULL, func, param) == 0) ? true : false;
+}
+
+void CloseOTTDThread(void) {return;}
+
+void JoinOTTDThread(void)
+{
+	if (thread1 == 0) return;
+
+	pthread_join(thread1, NULL);
+}