Starting kalman filter cleanup

Better kalman filter simulation

Oh hey I think the kalman filter works.

Goes a little crazy 'cause the measurements are bogus though.

Ok let's just do a Kalman filter for velocity or such

Then generalize it later.

fix module names

We now have a PID controller, huzzah!

EDoc isn't the worst!  Huzzah.

some docs

Refactor time server to use ETS

Works pretty okay!

trying to remember where I left off

references

Play with PX4 a little.

It's probably the Right Choice for flight control right now.

Add pretty_env_logger

And rayon; it has a threadpool, and we'll for sure want it for
other things sooner or later.

refactor out common stuff

fix timing bugs

Mocking out more sensor functionality.

Writing this like a game loop actually works okay so far,
if only because I know how to do it real well.

blorg

We now have a basic time server.

Harder than it looks.  Fuck you, time.

fix typo in module name

Turn localization module into a gen_server.

Actually works pretty well.