Refactor: Use only LaTeX3 syntax in LaTeX package.
Provide key=value LaTeX interface.
Provide LaTeX interface for debugging configuration (option key 'debug').

This setting was only available in the Lua API, so far.

Changes:

  * Debugging is now inactive, by default.  Both, in the Lua as well as
    the LaTeX API.
Update examples/MANIFEST.
Update .gitignore
Refactor: Separate debugging from manipulation information.

And rename some identifiers:

  is_debug_spots      =>  is_debug
  __cb_write_words()  =>  __cb_write_debug_information()
Refactor: Refrain from using global variables during node list scanning.

A closure factory has been introduced.  All state is now kept within
closures.
Refrain from providing call-back management.

There's no easy way for two packages to do pre- and
post-call-back processing independently.  A solution for that
problem is better provided outside of this package.  To make
things less complicated, call-back handling is left to the user.
example: Refactor: Add LaTeX packages to all LaTeX examples.
example: hyphenate-with-explicit-hyphen: Add more example words.