new pickup modes

[Peter Mardahl <peterm@soda.berkeley.edu>]

  I hacked in but didn't document the new pickup mode:

pickup 0-5 perform as before.

pickup <some larger integer than 5>
does this;  when you step on a square, it will
pickup all items of a value density greater than 
what you set pickup to.

value density is
<worth in goldcoints>/<weight in kilograms>

goldcoins have a value density of 66,
I find that
pickup 10
is very handy.  It will pickup silver, gold,
rings, wands, books, and scrolls automatically for you.
Artifacts are also picked up.

This takes away a lot of the mindlessness in the game:
you don't have to explicitly sort through all the garbage
to pick up coins.

The worth in goldcoins is what you would get by selling the
item on the ground as-is in a store--it will not 'identify' items
for you.

Regards,

PeterM