A functor provides the map operation that allows lifting an f
function into the functor context and applying it.
The purpose of this type-class is to support the data-types in the
Monix library and it is considered a shim for a lawful type-class
to be supplied by libraries such as Cats or Scalaz or equivalent.
To implement it in instances, inherit from FunctorClass.
Credit should be given where it is due.The type-class encoding has
been copied from the Scado project and
Scalaz 8 and the type has
been extracted from Cats.