First steps for supporting patch().
Merge branch 'patch-support' into master-v0.2
Now passing patch() tests.
observe. prefix for patch_map.
Merge pull request #199 from alxhub/master-v0.2

Now passing schema object tests for patch() support.
Reinstate multiplexer_test.dart
Delete obsolete runtime/entity folder
Reinstate batching tests
Reinstate branching tests
Adapt cache to new type system; reinstate tests
Reinstate dedup test
Reinstate error test
Fix transactional API codgen; reinstate tests