Enhancement: Render answers more nicely

[ericmjl]

This is a simple fix.

Instead of:

from nams.solutions import some_module
from inspect import getsource

print(getsource(some_module))

We do:

from nams.solutions import some_module

some_module??

This will render the outputs with colouring done right (at least in the notebooks)!

That said, I could be wrong, and it might instead break the LeanPub outputs (though I've never tried).