(kTextEncodingMacRoman, kTextEncodingISOLatin1)
(kTextEncodingISOLatin2): Remove constants.
(mac-script-code-coding-systems): New constant.
(mac-handle-language-change): New function.
(special-event-map): Bind it to `language-change' event.
(mac-centraleurroman, mac-cyrillic): New coding systems.
(mac-font-encoder-list, ccl-encode-mac-centraleurroman-font)
(ccl-encode-mac-cyrillic-font): Rename mac-centraleurroman-encoder and
mac-cyrillic-encoder to encode-mac-centraleurroman and
encode-mac-cyrillic, respectively.