Subclassed the clear method on Core so that object dictionaries can be purged without removing the pore.all and throat.all entries
Subclassed the clear method on Core so that object dictionaries can be purged without removing the pore.all and throat.all entries

PMEAL/OpenPNM,amdouglas/OpenPNM,amdouglas/OpenPNM,TomTranter/OpenPNM,stadelmanma/OpenPNM