Quash a load of compile warnings

Kevin Lyda writes:
I enclose the following patch which removes all but three of the warnings.  i
don't have any non-linux systems handy to test a fix to the round() function.
but having it return a double should be fine.

It doesn't actually fix anything, it just shuts up -Wall, so it's certainly an
optional type of patch.

main.h

@@ -32,7 +32,7 @@
 #define GOT_MAIN_H
 
 /* Function to clean up at end of run */
-extern volatile void MAI_CleanupAndExit(void);
+extern void MAI_CleanupAndExit(void);
 
 #endif /* GOT_MAIN_H */