[amiwm] add a new command action to rotate windows

This adds a command to iterate over the set of windows.  It's not
like alt-tab in ye olde windows world where you'd alt tab once to
switch between two windows, and then keep alt-tab'ing with alt down
to go through the window list.  For now it just literally iterates
through those windows.

This makes it a lot easier to work with a large number of open
windows without having to constantly use the mouse.

libami/mdscreen.c

@@ -22,6 +22,16 @@ int md_iconify(XID id)
   return md_command00(id, MCMD_ICONIFY);
 }
 
+int md_rotate_window_raise(XID id)
+{
+  return md_command00(id, MCMD_ROTATE_WINDOW_RAISE);
+}
+
+int md_rotate_window_lower(XID id)
+{
+  return md_command00(id, MCMD_ROTATE_WINDOW_LOWER);
+}
+
 int md_errormsg(Window id, char *str)
 {
   return md_command0(id, MCMD_ERRORMSG, str, strlen(str));