Phantasmal MAPD

The exitd keeps track of exits between rooms.  It works with the MAPD
as necessary, and registers exits with the objnumd.

API

  get_name_for_dir - takes an integer direction and returns its
     name as a phrase structure.  "North", for instance, might be
     in the "English" slot of the phrase.

  get_short_for_dir - takes an integer direction and returns its
     name as a couple of letters.  "N", or "NW" might be appropriate
     letters for English directions.

  direction_by_string - returns an integer corresponding to an
     English name or short name for a direction passed in.  This
     is meant for use with configuration files, not player input,
     since it's not localized.

  opposite_direction - returns the direction opposite the one
     given.  Takes an integer, returns an integer.

  get_exit_by_num - takes a number corresponding to an exit and
     returns the exit object it indexes, or nil if the number
     indexes no exit.

  add_twoway_exit_between - takes two rooms, a direction from the
     first to the second and two optional tracking numbers for the
     exits.  The function adds a simple two-way exit between them.
     The two halves of the exit lead in opposite directions, so
     north might go from room1 to room2, and south from room2 to
     room1.

  add_oneway_exit_between - takes two rooms, a direction from the
     first to the second and an optional tracking number for the
     exit.  The function adds a simple one-way exit between them.
     The exit leads in a single direction from room1 to room2.

  fix_exit - takes an exit, an integer type (1 for oneway, 2 for
    twoway, others possible,) and an integer link (the object
    number for the return exit (-1 if oneway) and updates the
    data structure to the newest format.  Look, glance, nouns,
    etc. are all defaulted to the direction.  Sets open to true,
    openable, lockable, and locked to false.

  clear_all_exits - takes a room and removes all exits from it
     and their corresponding return exits.

  clear_exit - takes an exit.  Removes that exit and its
     corresponding return exit.

  get_exit_segments - returns a list of the segments that MAPD
     tracks exits with.

  exits_in_segment - Takes a segment number and returns a list
     of integers representing the exit numbers contained in the
     given segment.

  get_all_exits - Takes nothing and returns all registered exits.

  add_deferred_exits - Takes nothing, attempts to resolve all
     current deferred exits, if any.

  num_deferred_exits - Takes nothing, returns the number of pending
     deferred exits.