Two important changes that I should have separated into 2 commits
1. The argument 'subdomain' has been replaced by 'labels' in many functions.  There are still more places to do this but the code works as is.
2. The label 'all' is now the master list of pores and throats for counting.  Most methods default to 'all', which now actually counts the elements in 'all'
Merge branch 'feature/MajorReno' of https://github.com/PMEAL/OpenPNM into feature/MajorReno

Conflicts:
	OpenPNM/Base/__Tools__.py
A few more updates to the 'all' and label conversion of last commit