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.
I think this is fixed.  Because the pressure unit is not an argument for npt_simulation, I had to find the intersection of indices for the input temperature and pressure values in the PhasePoints list.  This would break if the values for a temperature and pressure were the same, but the pressure unit was different, e.g. (273, 1.0, 'bar') and (273, 1.0, 'atm').  Would this ever be the case?