Function: register-input-method

Register INPUT-METHOD as an input method for language environment LANG-ENV.

INPUT-METHOD and LANG-ENV are symbols or strings.
ACTIVATE-FUNC is a function to call to activate this method.
TITLE is a string to show in the mode line when this method is active.
DESCRIPTION is a string describing this method and what it is good for.
The ARGS, if any, are passed as arguments to ACTIVATE-FUNC.
All told, the arguments to ACTIVATE-FUNC are INPUT-METHOD and the ARGS.

This function is mainly used in the file "leim-list.el" which is
created at Emacs build time, registering all Quail input methods
contained in the Emacs distribution.

In case you want to register a new Quail input method by yourself, be
careful to use the same input method title as given in the third
parameter of `quail-define-package'. (If the values are different, the
string specified in this function takes precedence.)

The commands `describe-input-method' and `list-input-methods' need
these duplicated values to show some information about input methods
without loading the relevant Quail packages. (fn INPUT-METHOD LANG-ENV ACTIVATE-FUNC TITLE DESCRIPTION &rest ARGS)