streamlined container interface (trunk only)

streamlined container interface (trunk only)

     Reduce the number of questions issued when applying or looting a
container, and offer the opportunity to put things inside before taking
things out.  Instead of "Do you want to take something out?  [:ynq]",
followed by "Do you want to put something in? [ynq]", this gives just one
prompt; the result is similar to menustyle:full where you start out by
choosing between out, in, and both.  There are now two additional choices:
reversed, for both in the opposite order, and stash, to put a single item
inside.  Prompt phrasing is rather clumsy; I wanted to keep it short:
"Do what with <the container>? [:oibrsq or ?]", where picking '?' pops
up a brief help window.  Inappropriate choices (like 'o'and 'b' when
container is empty) are suppressed from the prompt but still acceptable as
input; " or ?" is suppressed if the cmdassist option has been toggled off,
but entering '?' still works to get help.

     Menu mode wouldn't allow 'b' when inventory was empty, despite the
fact that first taking things out might change that.  Now 'b' is a viable
choice if the container isn't empty, and the new 'r' is a vialble choice
when inventory isn't empty even if the container is.