- changed _validate_mode to _parse_mode to match all other _parse_methods - added a single arg to force only a single mode, which also returns a string instead of a list
- changed _validate_mode to _parse_mode to match all other _parse_methods
- added a single arg to force only a single mode, which also returns a string instead of a list

stadelmanma/OpenPNM,PMEAL/OpenPNM,TomTranter/OpenPNM