Major refactoring

Major in the sense that the parent directory has changed, from src to
movement_validation.

Also __init__.py is simplified.  It's not BLANK at the root level
though, because otherwise you'd have to do this and this seems annoying:
from movement_validation.features.WormFeatures import WormFeatures

better to say (in my opinion):
import movement_validation

then you can refer to movement_validation.WormFeatures