Adding the final verion of the 'mock-up' we've been working on.  This has all the functionality we want, and a nice logical code flow.
- includes setters and getters for data, writing topology and goemetry data to the 'network', and fluid and physics data to the 'fluids'
- includes setters and getter for info, which is a new concise flexible way to store pore and throat labels, such as top, bottom, internal, etc.
- also uses the sort of inheritance heirachy that we want (generic_network holds the network query tools AND is subclassed by specific topology generators).