Added a 'unit' generator method to 'WellPointed'.

This allows (by roundabout means) for a more useful outlay of the 'MonadPlus' hierarchy, with a generic 'Hask'-derived instance.
Added 'concatMap' to 'Foldable' module.
Moved 'MorphObject' from 'Cartesian' to 'Curry'.

Updated vector example.