Psychrometric caching

Implemented caching on additional psychrometric functions and cleaned
up Psychometrics.[hh,cc] in general. Also changed array allocation in
PlantLoopSolver::SimulateLoopSideBranchGroup to improve performance.
So is there some minuscule chance that there could be duplicates?  Some combinations of temp and fluid type that yield the same hash?  This is primarily and academic question as I assume the chance is so extremely small that it is not a concern.