Partial fix for i18n problems

I've added some new files: src/cong-language.c and .h and rewritten the
parts of cong-dispspec.c that handle names and descriptions of
dispspecs.

There's now a general-purpose container for storing things that can be
per-language.  I plan to rewrite parts of the gxx code to use this as
well (the gxx code is a mess, and really should be rewritten).

The CVS version of Edit->Preferences should work a lot better for all
languages now.  I plan to do some polishing of it tonight (it will
probably crash if you try to save a dispspec right now), and hopefully
get it into a releasable state.

Dave