Use a flit-based backend?

[Steven Silvester]

I'd like to contribute a flit-based backend, which I think would greatly simplify things.

Instead of a 1000 line setupbase.py we could use an in-tree backend similar to what I tried in ipython/ipykernel#927.

I had to abort that one because ipykernel ships with multiple top level entities, but ipyparallel does not.

[Min RK]

I'd love that!