item action 'T' against covered armor

Using 'i'+menu choice for suit+'T' to try to take off a suit that is
covered by a cloak (or shirt covered by suit and/or cloak) wouldn't
do anything.  It should report that you need to take off the outer
garment first and then not take the chosen item off.

There is probably a simpler fix.  It took me a long time to figure
where things were going wrong and them cobble this together.

A big chunk of the diff for invent.c is just identation, surrounding
a one-line change there.

include/decl.h

@@ -475,6 +475,7 @@ struct instance_globals_i {
     /* invent.c */
     char *invbuf;
     unsigned invbufsiz;
+    boolean item_action_in_progress;
     int in_sync_perminvent;
 
     /* mon.c */