No more Maybe in the forward direction
Removed unused code; fixed some docs; added dependency
Moved contents of module Data.Iso.Core to Data.Iso
Renamed Iso -> Piso
Fixed docs to point directly at GHC bug
Removed unused code
Merge branch 'nomaybe'

Conflicts:
	Data/Iso/Generic.hs
	ExampleGeneric.hs
Fixed merge mistake
Removed Semigroup instance
Fixed warnings