test case for converting Vietnamese text to MARC-8

Signed-off-by: Galen Charlton <gmcharlt@gmail.com>
improve conversion of certain composed characters to MARC8

Some characters should not be fully decomposed
before converting them to MARC8.  This patch adds
a table of such characters, based on Annex A of
http://www.loc.gov/marc/marbi/2006/2006-04.html
and on some sample records provided by Jason
Stephenson of MVLC.

Signed-off-by: Galen Charlton <gmcharlt@gmail.com>
prepare for MARC::Charset 1.35 release

Signed-off-by: Galen Charlton <gmcharlt@gmail.com>