swapper.work_add and swapper.work_rm

[Mathsnel]

Trying the example run_sampler.py, i found two attributes that are not declared in the swapper class:
swapper.work_add
swapper.work_rm

run_sampler.py won't compile due to this issue.
This attributes are also present in NCMC Work Calculation.ipynb and SaltSwap Demo.ipynb.
Thanks

[jchodera]

@gregoryross : Do you happen to know what happened here? Is it possible not everything was checked in, or this code was on another branch?

[jchodera]

@gregoryross : These appear in the calc_gradients branch, which is 13 commits ahead of master:

https://github.com/choderalab/saltswap/blob/calc_gradients/saltswap/swapper.py

Is it possible you meant to merge those changes into master?