use a scheduler instead of an scheduled executor service for future/t…

…ask effects (atnos-org#74)

except for monix task which can be directly embedded into Eff and support timeout
functionality

added a convenience method to shutdown the execution services on futu…

…re completion

added notes for 3.0.3

added notes for 3.0.2

added notes for 3.0.1

minor notes edits

Fixed the memoization of async values. (atnos-org#49)

* fixed the memoization of async values.

each intermediate value of a Eff[R, A] must be memoized

* renamed the async interpreters

publish 2.2.0

published 2.1.0

published 2.0.2