This updates GenericEntry's filename handling to be more careful
about Mac OS Roman vs. Unicode. Most of the work is still done with
a CP-1252 conversion instead of MOR, but we now do a proper
conversion on the "display name", so we see the right thing in the
content list and file viewer.
Copy & paste, disk-to-file-archive, and file-archive-to-disk
conversions should work (correctly) as before. Extracted files will
still have "_" or "%AA" instead of a Unicode TRADE MARK SIGN, but
that's fine for now -- we can extract and re-add the files losslessly.
The filenames are now stored in CStrings rather than WCHAR*.
Also, fixed a bad initializer in the file-archive-to-disk conversion
dialog.