Use pprintpp if insalled

[sirex]

It would be nice if pprintpp would be used for pretty printing values if installed instead of build-in pprint. Or at least pretty printing function should be configurable.

pprintpp gives more readable output.

[alexmojaki]

This seems like a pretty good idea.

Before making changes on my side though, can you try using it with the following code:

import pprint
import pprintpp
pprint.pformat = pprintpp.pformat

That should make pp use pprintpp.

[sirex]

Well, that works, but does not look like a clean solution.

[alexmojaki]

@sirex see #33