Added a PrintableDict to misc.  This is returned when props() is called with pores or throats given.  Its basically a pretty_print dict for now.
Experimenting with dynamic property regeneration.
1. Methods now take a 'static' argument that can make a model just generate data once, then disappear forever (constants)
2. Geom/Phys/Fluid objects now take a 'dynamic_data' flag that invokes a clause in __getitem__ that regenerates the data when called
3. Otherwise you can 'regenerate' each object (phys/geom) then regenerate network/fluids to get the latest data
Made regeneration methods more robust...adding checks for property existence, give logger warnings, etc.
- Small cleanups
- _models dict is now an OrderedDict so that each model is called in the right order