Added a couple experiments to serv/visualize/test.py.
class track2: Use acceleration instead of velocity.

Testing so far shows this method isn't as good as using velocity.
Setting up for next tracking phase.
track.py: M paramater is now lambda(t) type.

The maximum speed is given by the duration of the transition.
Next, track2 will test an alternative approach to this problem.
Draw all possible edges and find the highest likelihood set of
transitions, assuming the transition speeds exponentially
distributed.
Merge branch 'master' into tracking
track.py: maxspeed_exp()

Exponentially decaying maximum speed of target, given duration.
This will be used as a parameter for the probability distribution
of transitions.
track.py: experimenting with tracking alg.
serv/visualize/plot_pos.py and cmake installation.
Added serv/visualize to cmake.
FIXME in serv/visualize/plot_{track,pos}.py.

Related to installation of overlay image.
qraat.track.maxspeed_{linear,exp}().

Added these as class methods so that they're accessible in the API.
Working on next step of tracking algorithm.
Notes for next phase.
track.py: Commited to looking at all transitions. Added notes.
serv/web: Added track visualization prototype.
web/tracks: Marcel's track interface prototype.
qraat.track.insert_db()
web/tracks: Updated track interface.
web/tracking-prototype: finished.
qraat.track.export_kml().