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/winhelp.c b/windows/winhelp.c
index 0019d0e..0dffbfa 100644
--- a/windows/winhelp.c
+++ b/windows/winhelp.c
@@ -7,7 +7,7 @@
 #include <string.h>
 #include <unistd.h>
 #include "debug.h"
-#include "windows.h"
+#include "wine/winuser16.h"
 #include "heap.h"
 #include "ldt.h"