Hexagon maps

[Jim Kingdon]

> What would be the impact of switching from a hexagon mapping system
> to a rectangular one?

The impact?  Well, one that springs to mind is that it would enable
doing a closer emulation of some non-xconq games.  There was even a
"chess" module in CVS for a while (although I think that case probably
has more problems than just hexes vs rectangular).

How easy?  Maybe easier than one might think - to a certain extent
dealing with concepts like adjacency is encapsulated in macros like
for_all_directions (and the rest of dir.h).  There's also a comment in
dir.h which mentions some other parts of the code which know about
hexes.

Of course, it would be useful to let a declaration in the GDL pick one
or the other, rather than just hardcoding rectangular.  Oh, and there
are (at least) two versions of "rectangular", depending on whether
diagonal moves are allowed.