Various one-liner fixes

- correctly sets rot_theta to ship rotation speed when
  moving in system

- adds 'dir' helper method to linear ms mixin

- adds flag toggling visited route ship graphic, default
  to false

- expand motel registry test, verifying location events
  run loop
Add attr to elliptical ms specifying dist loc can be from path

If dist exceeds path_tolerance, loc will not be valid in context
of the movement strategy
Handle Motel#rotated_angle edge case
Update version in Rakefile