[cctbxbb] Tidy up CCTBX

[Graeme.Winter at diamond.ac.uk]

Hi Rob

More thinking on this one, following from a little conversation over the weekend at this end

If we were looking to be able to package cctbx in a more Pythonic manner - i.e. to allow pip install - would it make sense to start at the bottom rather than at the top? i.e. libtbx - which is pure Python with deliberately no dependencies - would be a good place to start? The lower level code is also more static so a safer candidate for pip installing compared with some of the more rapid changing things…