data-aviary

Copperbox revision 915.

I've started a new package data-aviary to replace fun-extras. I aim to be a bit more systematic (and less subjective) in collecting combinators in data-aviary and when Wumpus is ready for Hackage, data-aviary should make a better companion library (the present incarnation of fun-extras could really be called stephens-favourite-functions and otherwise be rolled into Wumpus).