Checkpoint for global implementation.
Tests working via .global.
Global change notices.
MapChangeRecord
Only care about change notices if someone is listening.
Tests for new global.
Merge branch 'master' into global-view

Conflicts:
	lib/runtime/entity/wrapper.dart
	test/generated/addendum_test.dart
	test/generated/schema_object_test.dart
Merge pull request #109 from alxhub/global-view

Add GlobalView to Entity, so .global['foo'] can be used in addition to ['global.foo'].