(svn r5887) -Cleanup: move date related functions, defines and variables to date.[ch]

-Cleanup: fix whitespace related coding style issues in date.[ch]
-Cleanup: make original comments doxygen compatible and remove/change outdated comments

oldloader.c

@@ -18,6 +18,7 @@
 #include "depot.h"
 #include "network.h"
 #include "ai/ai.h"
+#include "date.h"
 
 enum {
 	HEADER_SIZE = 49,