fix #H4407 - avoiding floor-food while blind

fix #H4407 - avoiding floor-food while blind

Accept the 'm' prefix for eat, offer, and apply.

Allows 'me' to eat from inventory without checking for floor food.
Primarily for use after blind character used 'm<dir>' to move
somewhere without touching a suspected cockatrice corpse there.

'm#offer' and 'ma<let>' accomplish similar floor-object-skipping
when offering a sacrifice or applying a tinning-kit.  (All three
commands share floorfood() to pick the item to use.)

Report suggested replacing pick-from-floor followed by pick-from-
invent with use of slash'em-style pick-from-invent with explicit
pick-from-floor choice in list of inventory letters "[abc or ,]"
(slash'em used period for 'here'; I've always liked comma better
since the action is to pick an item rather than a location).  I
implemented that for nethack a long time ago, but it was mixed in
with other stuff that wasn't ready for prime time and vanished
when I lost access to the VMS system I used to use).

Using 'm' prefix to skip part of a multi-part operation is a lot
simpler to implement but doesn't include an in-game reminder that
it is available.

Revised Guidebook.mn is tested, Guidebook.tex is not.