arl / addrelative             Adds a relative direction

   Format:
      ;arl <type> <dir>
      ;arl <type> <dir> <abbrev>
                              Adds a relative direction

   Notes:
      Relative directions are used by a handful of worlds in which a room's
         exits change depending on the direction in which the character is
         facing (which usually means the direction from which the character
         arrived).
      Axmud stores relative directions in a circle which assumes that the
         character is facing north.

                       0 - north
         7 - northwest           1 - northeast
      6 - west                      2 - east
         5 - southwest           3 - southeast
                       4 - south

      As an example, Discworld MUD uses the following set of relative
         directions:

                       0 - forward
         7 - forward-left        1 - forward-right
      6 - left                      2 - right
         5 - backward-left       3 - backward-right
                       4 - backward

      Axmud translates a room's relative directions into primary directions,
         rotating the circle as required. For example, if the character is known
         to have arrived from the east, and is therefore facing west:

                       right (N)
         forward-right (NW)      backward-right (NE)
      foward (W)                    backward (E)
         forward-left (SW)       backward-left (SE)
                       left (S)

      Relative directions are stored in eight slots (numbered 0 to 7) which
         represent the rotating circle.
      This command adds a new relative direction and (optionally) its
         abbreviated form.
      <type> is one of the slots. It can an integer in the range 0-7, or the
         equivalent primary directions from the first circle above ('north',
         'southwest', etc). Both standard and custom primary directions are
         recognised. If the slot is already occupied, using this command again
         replaces the slot's relative direction.
      <dir> is a relative direction like 'forward'. If the world uses
         abbreviated relative directions, you can specify <abbrev>.
      If either <dir> or <abbrev> contain spaces, they must be enclosed within
         diamond brackets.

   User commands:
      arl / addrel / addrelative
