U234, buglist, and related iron ball bugs
Several bug reports have been filed regarding the use of attached iron balls to
move in ways that are otherwise disallowed: moving diagonally from a
doorway, moving through boulders, squeezing through small openings, passing
over traps and diagonally between boulders on sokoban levels. Modified
bhit to deal with this. All these cases now cause the iron ball to stop if
appropriate for your form, level of burden, and so on. Since both boulders
and iron balls are big, boulders now always stop thrown iron balls,
even if not attached. Since iron balls don't cause any damage as they pull
you along, I didn't add any damage for the new "jerks to a halt" cases.