pull request #1143 - menustyle:Full 'A' choice

Pull request from entrez:  in the class filtering menu for multi-drop
and for loot in-or-out of a container, make choosing 'A' without any
other filter choices (such as all, specific class(es), cursed, unpaid,
just-picked-up, &c) become a no-op.

I started with the pull request and then undid much of it.  It would
have been simpler to start from scratch.  If you don't have option
paranoid_confirmation:AutoAll set, when choosing 'A' for all-without-
prompting as the only selection, operate as the PR has made things
work:  effectively, 'A' by itself is ignored and the operation ends
with nothing happening.

However, if you do have paranoid_confirm:A set, then continue treating
'A' by itself as if 'A'+'a':  everything.  Since paranoid confirmation
is specified, that will be followed by a confirmation prompt.

This also adds a context-sensitive hint to the menu about how the 'A'
entry works, shown every time when 'cmdassist' is On or just once (per
session) when that is Off.

The documentation probably needs some updating.

Closes #1143

include/decl.h

@@ -147,6 +147,8 @@ struct instance_globals_a {
     int animal_list_count;
 
     /* pickup.c */
+    int A_first_hint; /* menustyle:Full plus 'A' response + !paranoid:A */
+    int A_second_hint; /* menustyle:Full plus 'A' response + paranoid:A */
     boolean abort_looting;
 
     /* shk.c */