devel/py-collections-extended: Add version 2.0.2

collections_extended is a pure Python module with no dependencies
providing extra collections. The new collections include bags AKA
multisets, setlists AKA unique lists or ordered sets, a bijection, a
RangeMap which is a mapping from ranges to values, and an IndexedDict
class. There are also frozen (hashable) varieties of bags and
setlists.

(gdt)