Sets: asTransient and asPersistent moved
Moved mass operation actions from ReadSet to PersistentSet
Moved mass operation actions from ReadMap to PersistentMap
Fixed asTransient / asPersistent stuff in set tests
PersistentSet#cartesianProduct now returns iterable
Set#filter added to PersistentSet interface and returns lazy iterable
Removed filter - just alias for where
Merge pull request #26 from vacuumlabs/strict_transient

Strict transient