Move DynamicEntity out of Streamy runtime and into testing library.
Turn .local into a plain Map.
Remove dependency on dart:mirrors from Streamy runtime.
Merge pull request #73 from alxhub/no-more-mirrors-or-nsm

Remove dependency of Streamy on dart:mirrors. Convert .local to a plain Map, and move DynamicEntity to the testing library. new Entity() is now a RawEntity.