Now we check a hash of the voice commands before writing the strings
file to reduce how much we write to the hard disk.  In implementing
this, I realized that some code was being duplicated in an easily
fixable way, so I created a Hasher object that keeps track of the
hash.json file.

Resolves #6

I truly am a modern Python man.

See commands.tmp for an example.  It's pretty neat, but it could still
use some work.  I thought of a really clever way to parse numbers, better
than the one I came up with last night, but since I have a working
implementation now I figure I'd better commit it.

We have a new bug which causes the dictionary to be updated every time the
program starts.  I hope I didn't force that to happen last night or
something, but I have a vague feeling I did.

At the same time, I moved the logic to check if the language should be
updated into the new LanguageUpdater class.  The README has been updated
to reflect the fact that you no longer need to do any of this manually
ever.