Issue with cookbook/choose_protocol.ipynb

[mikemhenry]

I am not sure of we need to define an __eq__ or something to make the assert more helpful, but right now it is hard to tell what is wrong (or even if there is a difference)

I could write a bit of python to loop through both objects, but for the sake of getting our new showcase out the door, I will just comment out this cell.

[richardjgowers]

the eq operator should be working fine, but it won't give you details on why. This was caused by us updating the default openff FF version, I've fixed this in #99

[mikemhenry]

#99 (comment)

tl;dr there was an issue with the FF version, but also with things like 25 != 25.0

[mikemhenry]

This PR #156 will re-enable the assertion check (which is handy to check if our default settings change)