Proposal: Use (.) and id from Control.Category in Prelude

[Carter Charbonneau]

(.) and id are generalized in the Category class in Control.Category. In 
the past, many libraries have instructed users to use (.) and id from 
Control.Category for composition of their types. Importing these types 
into Prelude shouldn't break existing code, and makes libraries that use 
Category easier to use.

Discussion period: 4 weeks