Updated the 'label' retrieval methods
- Now there is only 'labels', which is a counter-part to pores/throats.
- In pores/throats you send labels and get pores/throats, in labels you send pores/throats and get labels.
- Removed the deprecated methods since they weren't being used
- Changed they way 'labels' modes work.  There is no flatten, it flattens if the mode requires it.
Merge remote-tracking branch 'origin/feature/locations' into feature/locations