symset properties (trunk only)

symset properties (trunk only)

Pat Rankin wrote:
> Symbol set definitions need a description attribute, above and
> beyond allowing comments in the file, for inclusion in the 'O'
> command's menu entries for selecting them.
[...]
> mapglyph.c isn't the proper place to decide whether to define
> ROGUE_COLOR.  That may need to become a symbol attribute,
> which we'd then specify on the Epyx rogue set(s).

Implement both of the suggestions above.