Call Efuns

The following efuns deal with making, redirecting, and intercepting various
calls between objects.

<DL>
*  call_other
*  call_out
*  call_stack
*  catch
*  origin
*  previous_object
*  query_shadowing
*  remove_call_out
*  shadow
*  this_object
*  throw
</DL>

 Tim Hollebeek  Beek@ZorkMUD, Lima Bean, IdeaExchange, and elsewhere

