Altered the create_adjacency_matrix function a bit.  It now returns a matrix if no property is sent (ie. if you want to 'save the matrix' you must give a name to save it under..['lil']['throat.property'])
Improved printing
Small changes to incidence matrix to match adjacency matrix
Changed both create_incidence and create_adjacency_matrix
- They now ONLY return matrices.  The previous way was much too confusing about when a matrix was returned and when it was saved to the network object.
- All places in the code have been updated
- The code now saves the connectivity to the network (ones in all locations) for quick access later
Merge branch 'develop' into feature/better_props

Conflicts:
	OpenPNM/Utilities/__Tools__.py
Fixed Boundary to provide non-zero throat and pore area, for conducance calcs
Changed zero checking on linear solver, to be 1e-6 less than min conductance rather than 1e-30 (which was causing some singularities)
Minor tweaks to multiphase methods