* send ext.flutter.exit

* listen for help restart, quit

* refactor into a separate class

* add a service extension for repaint rainbow

* review comments

* download android-arm-deploy

* wire up --deploy to android-arm-deploy

* fix interpolation

* more terse flutter upgrade

* fix an issue when updating and the engine update code has changed

* call flutter precache; add a --no-color hidden option

* fix a lint related to getters/setters

* better messaging about windows support

* fix lints

* use --no-precompile

* use the flutter bin cache's sdk

* add cache.dart to help manage the cache dir

* sp