Moved pore and throat geometry functions to a models folder
Big batch of changes to the Geometry models
- They now all return values, instead of writing them to the network
While the add_property method is in GenericGeometry, it can append it's own pores and throats.  If this function gets moved to Tools, the pore and throats will be required as arguments.
- Converted fluid prop to return values,
- Updated add_properties to work with new style props
Changes to physics
updated all prop to accept variable prop names as arguments, like before.
Updated subclasses to use new add_property
Renamed BasePhysics to Standard
networks now print themselves
Reset all data to ndmin=1 in __setitem__
- why does this keep getting set back to 0?
- Starting to force all props to be vectors
- Try to create a property of Nt/Np length on demand
Decent version of __setitem__
- It now converts all arguments to vectors
- It does necessary checks on names, prevents wrong length vectors
- An empty label array can be created with pn['element.label'] = False since the False will be converted into a vector of the correct length in __setitem__
Merge branch 'feature/ImproveGetitem' into feature/better_props

Conflicts:
	OpenPNM/Fluids/__GenericFluid__.py
	OpenPNM/Utilities/__Tools__.py
Fixed throat label addition during TestNet generation
Merged new __setitem__ logic into Develop
- This commit removes a check from the _set_data method that prevented writing scalars into vectors.  All properties are vectors now, so this check was not valid.
- Also fixed some strange retrograde code problems in hydraulic and thermal conductance where the geometry object was passed in place of geometry.pores().  This hasn't be a valid maneuver in ages, so not sure how it crept back into the code.
Merge branch 'develop' into feature/better_props

Conflicts:
	OpenPNM/Physics/hydraulic_conductance.py
	OpenPNM/Physics/thermal_conductance.py
Readded legacy add_property to Geometry, change new method to add_model
Readded legacy add_property back to Physics
Readded legacy add_property to Fluids
First attempt to enable legacy add_property and new add_model in GenericPhysics/Geometry/Fluid
- Air uses add_property, and it works like before (requiring a call to regenerate)
- Standard physics uses a mix of add_model and add_property and it also work, provided that regenerate() is called to calculate the add_property properties