Cyrillic issues in 0.94.12

[Clint Adams]

> Unicode is a great thing, but as it was already noted here some
> time ago, Unicode will become really usable not sooner than Unix
> OSes get full support for it in screen drivers, user software etc.
> Until then, using national encodings is more convenient since a
> user can read the tokens from the terminal, debug wordlists etc.

bogofilter could use any Unicode encoding internally regardless of
the charset used for display.  It seems silly to me to waste code on
provincial encodings when all this could be done generically.