Using cobordisms to open and close braid caps in the computation of HF
and spectral sequence.
Relative gradings on cobordisms on linear PMC (larger PMC on the left)
and simple cobordisms (larger PMC on the right). Strengthened
registerHDiagram in DAStructure to deal with the case of two
generators x, y with arrow x -> y. This allows computation of gradings
on the chain complex when caps are opened and closed using cobordisms.