Fix threshargs, Use different outputname

	modified:   positions.py
Fixed verbosity

Added boolean variable `verbose` to stop most prints if False.

	modified:   tracks.py
some small fixes

 - include dotfix in TRACKS filename
 - actually use `taus` variable
 - isinstance() instead of type()

	modified:   tracks.py
Better normalization of final mean

Instead of number tracks, keep a new 'added' track that divides
differently for each value of tau depending on how many tracks that
cover up to that tau.

As of now, if a given tau has zero tracks, divide by one.  Should have
no impact?

	modified:   tracks.py
First go with otracks.

Doesn't keep track of turning number.

This shouldn't be its own file, but merged with orientation.py

	new file:   otracks.py
New function track_orient

tracks branch cut crossings and remembers turning number to have theta
unbounded over time.

Assumes that dtheta/frame is << 2pi

	modified:   orientation.py