changelog updates for 0.10.0 beta

...and the changelog while we're at it
align frame_demo files with dir name

add it to dart2js compile target
dart2js
hop_tasks: dart2js: added flags for liveTypeAnalysis & rejectDeprecatedFeatures

...use both of these features in the dart2js task for bot
calling v0.10.0 RTW
Merge branch '0-10-stable'