they used to do some other jobs than what done by
set-language-environment, those jobs are done in
setup-XXX-environment-internal now.
("LANUGAGE-ENVIRONMENT"): Delete property setup-function or change
the value to setup-XXX-environment-internal. Add properties
nonascii-translation, input-method, features, unibyte-syntax, and
unibyte-display.
internal -> emacs-mule, automatic-conversion -> undecided.
Coding category name changes as follows:
coding-category-internal -> coding-category-emacs-mule.
Delete functions describe-LANGUAGE-support.
Delete describe-function entries and change documentation
entries in each language specific information.
interactive and add new functions describe-LANGUAGE-support for
all LANGUAGEs supported. Remove resisterations of input methods
which use the function encoded-kbd-select-terminal.
