Add vision specific featurecoordinators

FeatureCoordinators for disparity, ocularity, spatial frequency and motion are added. This pull request depends on the related ImaGen pull request (https://github.com/ioam/imagen/pull/30). The motion feature coordinator needs time_dependent to be set to true.
The old Sweeper and the new Sweeper have fundamentally different concepts of how sweeping. I don't see an easy way of interchanging them. I thought we agreed in https://github.com/ioam/imagen/pull/30 that moving the old Sweeper code into lissom.ty is the way we want to do it?