comments
reorganize code
calibrate WingJ data
use parameters to denote files etc.
add docstring for wingj_dist_to_surfaces()
make movement vector calculation more flexible

the function movement_vector allows to specify an interval N, so the
movement is calculated between two spots that are N steps apart
calculate combined tracks directly
calculate movement with stepping 1 and 5
calculate rotation
add new results to CSV output
use numpy's option to write CSV
make px_size parameter optional
add todo