Allow for the parallel simulation and comparison of trjs with unique initial conditions.

Updating my branch.  I know I will need to change some networkx stuff, and I think the result file compression handling has changed.  This will impact how the parallel trajectory pickles are recombined.

I also added an isothermal compressibility target a few months ago - it's useless (for now) as the needed sampling is on the order of 100 ns.
For water this is not the case.  Would it be okay to load the pressure unit for each point separately?  (It's not a big deal since bar vs. atm is only a 1% difference anyway.)