Use update-in-place in sequential vectors for efficiency
Generalize the types of map and repeat in Feldspar.Stream

These functions don't need the constraints in the types
Add Functor and Applicative instances to Stream
Add a few functions to Feldspar.Vector.Push
Fix the types in Feldspar.Vector.PullPush
Update Feldspar.Vector.PushMultiDim to use the new Feldspar.Vector.Shape