The plugins shouldn't be in charge of running the
valid_sentence_command.  They also certainly shouldn't have to manage
the history file.  Both of these functions have been delegated to the
Kaylee object, by way of a 'processed' signal emitted by a plugin as
soon as it knows it will handle the voice command.

Since Kaylee now supports Python plugins that can do arbitrary things
with spoken words, the pass_words option for shell commands seems
somewhat less necessary than before.  I never liked it in the first
place, because it was all-or-nothing: there was no non-hackish way to
pass the spoken words to only specific commands.  If I ever see a
compelling reason for this feature to come back, it may be
re-implemented in the form of a second shell plugin that passes words to
its commands.

As part of the effort for resolving #12, I've started work on a plugin
API for Kaylee.  While very much a work in progress, it will allow
Python plugins to be written, loaded from user configuration, and
hooked in to events from necessary portions of Kaylee to handle voice
commands.

Currently there is only one plugin, a partial implementation of shell
command support as existed previously.  It works in that it executes
commands, but several old features are missing.  Also, the GUIs are
probably broken, but I'm not worried about that at the moment.

Recognizer.commands was unused, so there's no reason to keep it.

I spelled it "fourty", which tricks the lmtool into making it much
harder to recognize the word.  Now it's spelled "forty", which makes it
much easier to understand.

This makes pocketsphinx pick up way fewer false-positives of single
number-words as recognised sentences.  It doesn't seem to make any
difference in anything else, but fewer false-positives is always nice.

They still need work of course, since I'm a programmer and not an
artist.  The new icons of course are Kaylee's parasol, and anyone who
doesn't know that needs to watch Firefly.

The argument parser isn't part of the API of the Config class, so now
its name reflects that.

Commands aren't stored in a special file anymore, and Kaylee never tries
to look at that file.  Therefore, there's no need for the Config object
to keep that file's path, and so the path has been removed.

Added some blank lines and wrapped some long lines to be closer to PEP 8
compliance.

Improved docstrings in NumberParser class.  Added docstrings for
undocumented code and removed a TODO message that no longer applies.

Apparently CMU thinks it's a good idea to release a new version of a
piece of software that breaks existing APIs without even changing the
version number.  I find this idea to be highly dubious at best.
Nevertheless, I have updated Kaylee to support the latest version of
pocketsphinx.

That's "Kaylee Voice Command" if you didn't figure it out.  I think
everything still works properly, but I'll do more testing later to
verify.