Commands for changing character sets in richtext:

Japanese:

<iso-2022-jp>		ISO-2022 encoding for mixed US-ASCII and JIS.
<x-jis-x0201-1976>	Variant of US-ASCII for Japan.
<x-jis-x0201>		Variant of US-ASCII for Japan.
<x-jis-x0208-1978>	JIS X 0208-1978
<x-jis-x0208-1983>	JIS X 0208-1983
<x-jis-x0208>		JIS X 0208-1983

Korean:

<iso-2022-kr>		ISO-2022 encoding for mixed US-ASCII and Korean.
<x-ksc-5601>		2-byte encoding of Hangul without shift/escape seqs.

Internal commands:

<x-iso-2022-gen-HH>	Used for ISO-2022 escape seqences.
<x-iso-shift-in>	SI character
<x-iso-shift-out>	SO character
<x-iso-charset-HH>	Used for ISO-2022 ESC$)? character set designators.

Notes:

<iso-2022-*> text sequences may contain ISO-2022 escape sequences for changing
character sets.  <x-jis-*-*> and <x-ksc-*> text sequences can also contain
such escape sequences, but they start out in 2-byte mode, and are intended
mainly for 2-byte character sequences, rather than a mixture.
