* move flutter user analysis options file
* add comments referencing each of the analysis options files

The old release contained some unused files that caused trouble on the Windows Chromebot.

* Add platform_services sample

* update build.gradle to use latest scripts

* use FlutterActivity

* Updated ExampleInstrumentedTest.java and deleted FlutterPlugin.groovy

* Remove getRandom code from main.dart

* remove unused import

Previously the "left" padding was applied on the right when hit testing
a reversed vertical list view.

This test was a bit tricky to convert because it subtly relied upon the
lazy evaluation of an Iterable.

The onDismissed from Dismissable happens during the animation phase of
the pipeline. Previously, the ScrollableList had already been built for
that frame but had not evaluated its Iterable yet. When we got to the
layout phase, ScrollableList evaluated its Iterable and saw the updated
version of dismissedItems.

A straightforward conversion to ListView calls toList() when building
the ListView, but that evaluates the iterable when buildTest() is
called, which is before the calls to pump and therefore before the
animation phase, meaning the Iterable sees the old value of
dismissedItems.

This patch fixes the test to use the normal setState pattern to signal
that state upon which the build depends has changed. Now, the
onDismissed callback happens during the animation phase and the
StatefulBuilder is marked as dirty via setState, which causes it to
rebuild the ListView and re-evaluate the Iterable, seeing the updated
version of dismissedItems.

This change also lets us replace the gratuious use of pumpWidget with
pump now that we use setState rather than pumpWidget to trigger a
rebuild.

Clients should use ListView instead.

We've decided not to store the scroll position in PageStorage because
routes now maintainState by default.

Fixes #8051

The last remaining client is complex_layout.

They previously were very sensitive to widgets like LayoutBuilder.

These now test ScrollNotification2.

Replace version-specific link with a version-independent URL.

See https://github.com/flutter/flutter/issues/7579

This used to be the logic before I made the tests portable.

Fixes https://github.com/flutter/flutter/issues/7974

* Make new project template gradle-based for Android.

With this change, the 'new project' template uses the same gradle-based build for Android as the hello_services example. This has some implications on build performance, since we're now building a complete Android app instead of just combining a pre-compiled .dex with the Flutter assets.

The very first build is a little over 2x slower, since it needs to download gradle and build the build scripts before getting to the actual code. Subsequent builds with changes to the code are comparable to the old builds. Null builds are faster. Enabling the gradle daemon speeds up subsequent builds by around 5s.

* Move Flutter Gradle plugin to Flutter root.

Having the drawer docs lead with "this is a drawer" wasn't very
helpful when scanning.

qv. study P6.

Fixes https://github.com/flutter/flutter/issues/7963

Required to support Flutter SDK paths with spaces.

Required to handle Flutter SDK (and other) paths that include spaces.

Also includes general cleanup:
* Declare explicitly that we use /bin/bash, since we rely on its
  features.
* Add -- where possible, to avoid interpreting files starting in - as
  options.
* Suppress output of pushd/popd.
* Avoid stringifying arrays.

We call the builder in slightly different ways, but the new results
seem reasonable.

* Support changing the dismissable threshold for any direction for dismissable widget.

* Fixing review comments.

All the clients have migrated to GridView.  Also, remove RenderGrid,
which isn't needed by GridView.