Move the CTF save/load code into the ensemble.ctf.utils package.
Bring in the CtfManager class from the demo/volume-sandbox branch.
Remove the useless ICtfManager interface class.
Fix some missing pieces in CtfManager
Remove the context menu saving & loading of transfer functions.
Add CtfManager usage to the CTF example code.
Add unit tests for CtfManager.
Give PiecewiseFunction a more sensible default keyfunc.
Handle strange CTF names.
Flake8
Merge pull request #22 from enthought/feature/ctf-manager

Add the CTF management code from the demo/volume-sandbox branch