Optimized include/*.h: (recursively) include all headers needed by
this .h file, but only those. Necessary fixes to a lot of .c files,
started optimizing "windows.h" away from some of them. Moved
GetCurrentTask prototype to wine/winbase16.h.

diff --git a/include/shell.h b/include/shell.h
index 0ccd1df..b6f488f 100644
--- a/include/shell.h
+++ b/include/shell.h
@@ -4,9 +4,8 @@
 #ifndef __WINE_SHELL_H
 #define __WINE_SHELL_H
 
-#include "windows.h"
-#include "winreg.h"
-#include "imagelist.h"
+#include "wintypes.h"
+#include "windef.h"
 
 
 /****************************************************************************