MHonArc 2.1.2 bug with Japanese messages

MHonArc Users,

There is a bug in v2.1.2 that will cause MHonArc to go into an infinite
loop and cause an "Out of memory error" if processing ISO-2022-JP
messages.  The reason for the bug was my careless when cleaning up
the ISO-2022-JP code.

If you process ISO-2022-JP messages, replace the mhtxtplain.pl
file with the one from v2.1 for now.  A fixed mhtxtplain.pl will
be in the next release.

        --ewh