Quick stab at Unicode for AWGS/Teach

This tweaks the output for AWGS and Teach Text to convert from Mac
OS Roman to Unicode, rather than Windows code page 1252.

It would be slightly more efficient (and possibly a bit more legible
in the RTF file) if we left the "good" conversions alone, e.g.
continue to use the CP1252 character for "E with acute", instead of
converting to U+00C9.  That might leave us at the mercy of the code
page converter in some random RTF reader, though, so it's probably
best to just use the official Unicode values.