Make E subtype of Throwable

[Widar91]

No description provided.

[VledicFranco]

There is also a bigger discussion to be solved In issue #7

[kolov]

E is not necessarily a Throwable, in fact I use it with E being something like Error(code: Stong, msg: String)

[VledicFranco]

The thing is that this may be the only way of implementing the Effect[F[_]] typeclass from cats effect, Effect extends eventually from MonadError by setting the error to Throwable :/