[crossfire] no_pick 1 on earthwalls

[Mark Wedel]

  anyone know of a particular reason that earthwalls have no_pick 1 set?

  Earthwalls are 'alive 1', so can't be picked up in any case.

  Where this comes up is related to stacking and the new code - the new stacking 
code tries to put objects of specific types on specific layers (so monsters will 
be on top of objects, spells on top of monsters, etc).  Some maps hide things 
behind earthwalls, and since no pick objects are a lower layer than pickable 
objects, this results in objects no longer being hidden by the earthwall, and 
instead are now on top.

  I removed the 'no_pick 1' from my test server, and at a brief check, 
earthwalls behaved the same (had to whack them to destroy them).

  But before committing that change, just thought I'd ask to make sure no one is 
aware of any other problems.