gen dartdoc using the flutter styles

Switch docs to docs.flutter.io

That site is now live.

See if fixing indent fixes our missing caching

@abarth

rev engine

Fix formatting issue

Add nicer logging/reporting to dev/update_packages.dart

Makes it more obvious where we are spending our time on Travis.

Also added travis caching for the global pub cache to
speed this up!  Modeled what dartdoc does:
https://github.com/dart-lang/dartdoc/blob/master/.travis.yml#L13

@Hixie

Rename stocks/tests to stocks/test

This matches the naming pattern expected from package:test
`flutter test` doesn't care, since it finds all _test.dart
files and runs them regardless of directory.

@Hixie

Fix build breakage

Split out Instrumentation logic from WidgetTester

This will allow writing tests/benchmark which want to use
the engine's default beginFrame and normal passage of time.

@Hixie

Always import our packages when analyzing.

Only set tolerance if simulation is non-null

Fixes #898

Update SoundEffectPlayer to use the SoundPool API

Tabbar view swipe

Swiping left or right in a TabBarView now changes the selected tab in the way it's supposed to.

Currently swipe gestures that start while the selection change is underway are ignored. Will fix that in a separate change.

Swiping left or right in a TabBarView now changes the selected tab in the way it's supposed to.

Currently swipe gestures that start while the selection change is underway are ignored. Will fix that in a separate change.

Analyze more tests.

Use Scheduler.instance in flutter_sprites

support mini fabs

Rename Pointerer to Gesturer.

Refactor bindings.

Avoid rebuilding entire app when an overlay needs updating

Use hashValues instead of hard-coded hashCode getters

rev the engine

Minor fixes in comments and style.