(svn r2663) Include variables.h only in these files which need it, not globally via openttd.h

openttd.h

@@ -72,6 +72,8 @@ typedef uint16 StringID;
 typedef uint16 SpriteID;
 typedef uint32 PalSpriteID;
 typedef uint32 CursorID;
+typedef uint16 EngineID; //! All enginenumbers should be of this type
+typedef uint16 UnitID;   //! All unitnumber stuff is of this type (or anyway, should be)
 
 typedef uint32 WindowNumber;
 typedef byte WindowClass;
@@ -546,6 +548,5 @@ enum {
 VARDEF byte _no_scroll;
 
 #include "functions.h"
-#include "variables.h"
 
 #endif /* OPENTTD_H */