github pull request #228 commentary follows:
This adds a boolean option, autounlock, defaulting to true. When this is
set to TRUE, messages stating that some door or container is locked are
automatically followed by a prompt asking if you would like to unlock
it, if you are carrying an unlocking tool (key, lock pick, or credit
card).
Architecturally, this extends the pick_lock function to take three
additional arguments (door coordinates or a box on the ground you are
autounlocking).
Because this adds a new field to struct flag, this is not a
save-compatible change. I have not adjusted EDITLEVEL or
VERSION_COMPATIBILITY, though.
The code that selects an unlocking tool will always look first for a
skeleton key, then a lock pick, then a credit card. Since curses, rust,
and other attributes don't really have an effect on the viability of the
unlocking device, it didn't seem to warrant making a more complex
function for that.
closes#228
57861ab51d