fix char string corruption with xcsv. (#455)

fix char string corruption with xcsv. (#455)

Any gmsd char string data handled by the xcsv format could be
corrupted when main ran cet_convert_strings.  The xml format
reader/writer use a QTextCodec to handle all char string conversion,
but the data was converted again by cet_convert_strings ... garmin_fs_convert
to/from ASCII, resulting in corruption.

Add a test case for the above.

Add xcsv format support for gmsd email field.