Moved tweak support to USER dll. Removed tweak.h and cache.h.

diff --git a/controls/button.c b/controls/button.c
index d75004d..1983dd1 100644
--- a/controls/button.c
+++ b/controls/button.c
@@ -13,7 +13,7 @@
 #include "wingdi.h"
 #include "wine/winuser16.h"
 #include "controls.h"
-#include "tweak.h"
+#include "user.h"
 
 /* Note: under MS-Windows, state is a BYTE and this structure is
  * only 3 bytes long. I don't think there are programs out there