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/windows/nonclient.c b/windows/nonclient.c
index 36efbdd..bf58c52 100644
--- a/windows/nonclient.c
+++ b/windows/nonclient.c
@@ -23,6 +23,7 @@
 #include "tweak.h"
 #include "debug.h"
 #include "options.h"
+#include "shellapi.h"
 #include "cache.h"
 
 static HBITMAP16 hbitmapClose = 0;