engraving with stack of cursed weapons

engraving with stack of cursed weapons

Fix a FIXME added for issue #1233.  When engraving, if the writing
implement is a stack of cursed weapons which are welded to the hero's
hand, just write in the dust rather than engrave in the floor, in
order to keep the whole stack welded.

Only applies when the stack is actively welded.  Other stacks of
cursed weapons will have one split from the stack to perform the
engraving, otherwise engraving could be used to determine whether a
stack is cursed without the risk of wielding it.