* Split didPush() into didPush() and install(), so that we can install
  the overlays without triggering the push logic. This will be used in a
  subsequent patch to implement route replacement.

* Split didPop() into didPop() and dispose(), so that we can remove
  overlays without triggering the pop logic. Also for a subsequent patch
  that implements replacement.

* Clean up _navigator on the routes when the Navigator itself is
  disposed.

* Drop the forwarding logic on willPushNext() -- now didPushNext() --
  and didPopNext(), since we no longer have StateRoutes to get in the
  way.

* Implement isCurrent more broadly and without having to keep track of
  state.

* Provide some toString()s on NamedRouteSettings and ModalRoutes.

* Make OverlayState.initState() use the insertAl functionality.

* Make OverlayRoute.builders abstract since that way you'll catch when
  you forget to do it. If you don't want overlays, don't inherit from
  this class.

* Made handleStatusChanged() on TransitionRoute public so that it can be
  overridden by subclasses.

Animate slider radial reaction

Also, have the slider draw different in its disabled state.

print logging timestamps to profile app launch

allow logs to work from any location

Add a basic material slider

Finish TimePicker

The slider in this patch works, but it's missing animations and many subtle
touches.

After this patch, TimePicker should work correctly.

Fixes #559

Opacity was dropping stuff on the floor.

Turns out we passed the wrong bounds to the PaintingContext constructor.

Fix, and assert that we don't do that again.

Rev the engine dependency to the latest engine.

fix analysis errors; add missing icon

Remove start_test

This test was a bad mock-based test that hasn't ever caught a bug but has
required a lot of maintenance. Currently its broken because its mock doesn't
match the real interface.

Add support for system-level routing

Now you can supply a route argument to flutter start:

  $ flutter start --route /foo

which will start the app at /foo instead of /.

Update to a new engine release

Teach the TimerPicker how to pick a time

The TimePicker can now actually pick a time. However, it doesn't understand AM
or PM and there's lots of visual polish missing.

Remove StateRoutes

Hide pub get output when updating flutter tool

Pin `package:test` to an exact revision

We use a number of non-public APIs in the test package, which makes our
dependency quite fragile. This patch pins a specific, known-good version. We
should update to the lastest version in a follow-up patch.

ignore .atom directories

Start working on a TimePicker

Improve unauthorized regexp

Fixes https://github.com/flutter/flutter.github.io/issues/101

Fixes https://github.com/flutter/flutter.github.io/issues/100

Expose the navigator in routes.

You can't actually pick a time with the time picker yet, but this patch adds
most of the plumbing.

Add drop down buttons to Material Gallery