Added (spherical) exclusion ranges to @recvim, @startim and @sendim

  -> Examples:
      * @recvim:0,20=n   - user can only receive IMs from people within chat-range (20m)
      * @sendim:256=n    - user can only send IMs to people who are at least a region away (256m)
      * @startim:0,256=n - user can only start IMs to people who are on the same region they are (between 0moh oh and 256m)
  -> Note that you generally can't rely on having location information for avatars beyond the current region (and maybe 1-3 surrounding neighbours) so large values are of limited use
  -> On an isolated region using 4096m as the upper value will guarantee that you can only IM avatars on the same region regardless of elevation but none anywhere else on the grid

--HG--
branch : RLVa