old changes to orientation.ipynb

Nothing fancy, just failed to commit them earlier.
Better capability to limit the analysis in each block.

	modified:   orientation.ipynb
Add command line arguments for dot sizes

For easier testing and changing purposes, the sizes for the convolution
kernel and for the region filters (area and eccentricity) can (must at
this point) be specified from the command line.
TODO: Better defaults should be set once they're determined.

	modified:   positions.py