Replacing UTF8 strings with regex

Thanks for fixing the use of UTF-8 strings in selections (Issue #61 (closed)). There are still an error when trying to replace a string with UTF8 chars, e.g.,

# working filter
=C filter --replace /György/Baldoví/c

# crash
=C filter --regex /Александр/Peña/c

traceback.txt utf8.fi