[Lazarus] MaskEdit and Utf8 support

[Bart]

Hi all,

I implemented Utf8 support for the maskedit unit in r39175.
Since this is a major rewrite, I may have introduced new bugs or even
regressions ;-)

See also the "Known issues" comments in maskedit.pp

Can you please test and report any found issues, preferrably in the
bugtracker (and assign them to me, if you have proper rights in
mantis)?

Thanks in advance.

Bart Broersma