[crossfire] Default hp/sp for exits

[Preston Crow]

I would like to set the default hp/sp in the archetype for exits to -1, 
which would make the default be to use the enter_x/y values for the 
target maps.  I expect these values are always overridden in the maps, 
so the impact should be minimal, and it would make it cleaner when using 
a map's default entrance.  My thinking is to encourage the use of the 
default entrance, as it makes it easier to redesign a map without having 
to modify the maps that link to it.  (I ran into this on my server 
adjusting pocket reality maps, and I had to modify all existing 
apartments to make the changes work cleanly.)

I expect there are maps where the exit target is zero in one of the two 
coordinates.  Since doing a mix of default and specified coordinates is 
probably a bad idea, I would have the server convert a single -1 to a 
0.  I would then only need to search through the maps for any exits with 
a slaying field but not hp or sp, just in case there are any 0,0 exits 
on purpose.

I noticed a recent commit to all the guild maps to correct an exit 
coordinate, which might have been avoided by using the map default, but 
I'm not proposing a mass change to existing exits to convert them 
(eliminating coordinates on exits if they match the defaults for the 
target map), though that might not be a bad idea.