Removed differently typed getValue and setValue and turned into getter / setter with onUpdate stream.  Refactored accordingly.
Update (now updated) gets fired on finish of update and added onChanged gets fired immediately when a value is changed (for data binding).
Merge branch 'umop-preferences_phase1' of https://github.com/dart-lang/chromedeveditor into umop-preferences-json_cached
add a new cde_core package
fix an issue with importing files
Cleanups in UI messages
Merge pull request #3294 from ussuri/small-fixes-3

Cleanups in UI messages
Patch: spark-button wouldn't hightlight on hover
Merge pull request #3295 from ussuri/fix-buttons-not-highlighted-in-deployed

Patch: spark-button wouldn't hightlight on hover
Merge pull request #3293 from devoncarew/devoncarew_fix_import

fix an issue with importing files
Whitespace
Merge pull request #3298 from ussuri/minor-cleanups

Whitespace
Don't mention unfinished git pull/push/merge in changelog.md
Merge branch 'umop-preferences-json_events' of https://github.com/dart-lang/chromedeveditor into umop-preferences-json_events
Merge branch 'master' of https://github.com/dart-lang/chromedeveditor into umop-preferences-json_events
Review fixes
Merge pull request #3272 from dart-lang/umop-preferences-json_events

JSON events (update and changed) in preferences
add an adaptable pattern class
nits
Merge branch 'master' into devoncarew_cde_core