Moves more stuff from windows.h.
- include/winuser.h - interface relevant to user32.spec
- include/wine/winuser16.h - the old 16 bit interface (internal use)
- include/winbase.h - some minor updates to keep things coherent.
- Lot of other files made to include wine/winuser16.h, which is no
  longer included from windows.h

diff --git a/windows/defdlg.c b/windows/defdlg.c
index 5a7412d..dc273aa 100644
--- a/windows/defdlg.c
+++ b/windows/defdlg.c
@@ -5,7 +5,7 @@
  *
  */
 
-#include "windows.h"
+#include "wine/winuser16.h"
 #include "dialog.h"
 #include "win.h"
 #include "winproc.h"