My version of a GenericFluid class
* James: I deleted a bunch of your methods only because I wanted to see the bare behavior.  I envision your methods being readded.
* At the moment it returns a dictionary.  I'd like to to have more methods, such as update.
Attempting to associate fluids (phases) with a specific pore network
More or less complete prototype now
* The fluids are NOT generated, they are SPECIFIED by a set of parameters that dictate how to predict properties, like a recipe
* A recipe for each is stored on a network under pn.phases[name']
* The network updates its fluid properties by combining its conditions with the fluid recipe
* Also included an example subclass of GenericFluid for Water, which mearly contains the specific recipe for water
* This is either genius, or completely ridiculous.  We'll see in the morning.