utf32 in place

hi again,

utf32 encoding schemes implementation in hackerlab should be completed
in my latest patch (patch-9). i've also taken the liberty of modifying
what-is-unicode.doc, throwing in a couple of paragraphs on UTF-32.

next thing will be unit testing of utf32 and the _fw functions to be
used by pika.

sorry for bothering you with this micro-advance reports: i just want to
be sure that i'm on the right track, specially regarding in which
hackerlab (sub)lib my changes should go --- i promise to wait until i
have implemented something more substantial to post again :))

btw, tom: in the unicode code, the magic values 0xffff and 0xfffe are
used a lot: would you mind my giving them a name (via a #define or a
const declaration) and update their usage accordingly? if not, any
suggestion for their names? 

jao