Interface for TFManage.

[jparkhill]

After the water paper, we need to consider doing away with TensorMolData altogether, and cleaning up the file names, evaluation routines and overall interface for TFManage. It's gotten way out of hand.

[jeherr]

In TFBehlerParinello all dependence on a TensorMolData object has been removed. IMO this makes the need for a Manager object unnecessary altogether, as basically it's just acting as a medium to pass things back and forth between the networks and other parts of the code.