Consistent datatypes in scalaz.

[GodPlaysChess]

scalaz introduces better versions of the standard datatypes, such as
==>> (Map),
Maybe,
IList , but does not use it itself (for instance Map api returns List instead of IList and Option instead of Maybe) , which makes very cumbersome to utilise them.

I identified those places:

DataTypes:

• IList
• ==>>
• These
• Ephemeral Stream

Typeclasses:

• Enum
• Foldable

I discussed it in gitter and going to link corresponding PRs to this issue.
I think it makes sense to change Foldable and Enum typeclass as well. What do you think?