Added preliminary code for __getitem__(), __delitem__(), add(), remove(), clear(), keys(), values(), groupby().
Added preliminary code for __getitem__(), __delitem__(), add(), remove(), clear(), keys(), values(), groupby().

datreant/datreant.core,datreant/datreant,datreant/datreant,datreant/datreant.core,dotsdl/datreant