Standardizing interface for positions and tracks.
Tracker takes in a Position object.
Track.table same semantics as Position.table.
qraat.position.Bearing constructor.
qraat.track.Track constructor.
Track.insert_db(), executable serv/track/rmg_track.
Nitpicking ...
Using depID's instead of txID's, where possible.

We're holding off on altering `qraat.est` until all the pieces
are in place. TODOs in position.py related to this.
Install rmg_track, template for rmt_track_auto.
Another TODO.