more fighting boulders (trunk only)

more fighting boulders (trunk only)

     Followup to yesterday's "you attack thin air" fix for when there's a
boulder at the target location:  if wielding a pick-axe or mattock and you
use F to explicitly try to attack a boulder, dig the boulder to break it.
Also, treat statues like boulders:  F at them gets "you harmlessly attack
a statue" for non-pick weapon, or digs/breaks statue when wielding a pick.
Classified as a new feature in the fixes file.