The dartdoc will continue until morale improves.

This matches the pattern from Rect. I've left EdgeInsets.TRBL marked as
deprecated to give clients a chance to update.

Fixes #2860

* justifyContent -> mainAxisAlignment
* alignItems -> crossAxisAlignment
* FlexJustifyContent -> MainAxisAlignment
* FlexAlignItems -> CrossAxisAlignment

Fixes #231

This patch renames StatelessComponent to StatelessWidget and
StatefulComponent to StatefulWidget.

Fixes #2308

Fixes #1382

Fixes #1278

And fix the zillion issues that uncovered.

This reverts commit f41b3411, reversing
changes made to e33d8d96.

This was a bad check-in due to my mangling uploading a new version of the branch from a different machine.

This reverts https://github.com/flutter/flutter/pull/2639 and will be replaced by https://github.com/flutter/flutter/pull/2640

And fix the zillion issues that uncovered.

These files are already in the "material" folder. They don't need to be
prefixed with material again.

Fixes #702

Each layer is supposed to reexport the parts of the previous layer
that are part of its API.

- In painting.dart, export from dart:ui all the Canvas-related APIs
  that make sense to be used at higher levels, e.g. PaintingStyle.

- Delete painting/shadows.dart. It was dead code.

- In rendering/object.dart, export all of painting.dart.

- In widgets/basic.dart, export all of painting.dart and
  animation.dart. Some classes in animation/ are renamed to make this
  less disruptive and confusing to the namespace.

- Split out Stocks back into an import model rather than a part model,
  so that it's easier to manage its dependencies on a per-file basis.

- Move Ticker to scheduler library.

- Remove as many redundant imports as possible now.

- Some minor nit picking cleanup in various files.

This patch removes Performance and AnimationValue now that we've ported the
framework over to AnimationController and Tween. This patch also cleans up the
names of the AnimationController classes now that they don't have to avoid
conflicts with the old animation API. Specifically, I've made the following
renames:

 * Animated -> Animation
 * Evaluatable -> Animatable
 * PerformanceStatus -> AnimationStatus

This patch is just renames and moving code around. There aren't any changes in
behavior.

This patch moves Navigator and related code over to using
AnimationController.

Also, clean up the class hierarchy for AnimationController now that
we've renamed progress to value. That means everything in the hierarchy
now has a value, include Watchable. This patch renames Watchable to
Animated<T>, which lets us use that type almost everywhere.

I've added some ducktape to modal bottom sheets to avoid having to
refactor all of Navigator to use AnimationController. I'll remove the
ducktape in the next patch.

Previously we used a positional argument for widgets that had multiple
children. Now we use a named argument that defaults to an empty list.

Fixes #241

Instead of separate functions for the 0->1 and 1->2 transitions, just
have one function.

To make it easier to avoid pushing twice in one frame, provide a
transaction mechanism for the navigator.

- Removed the concept of ephemeral routes.
- Renamed the two _MenuRoutes to _PopupMenuRoute and _DropDownRoute.
- Added type arguments in various places:
  - DropDownMenu
  - _DropDownRoute
  - _ModalBottomSheetRoute
  - PopupMenuItem
  - _PopupMenu
  - _PopupMenuRoute
- Made _ModalBottomSheetRoute, the two ex _MenuRoutes, and _DialogRoute
  all inherit from ModalRoute, via PopupRoute.
- Change "Dropdown" and "DropDown" to "DropDown" consistently.
- Made MaterialPageRoute inherit from PageRoute.
- Made ModalBarrier not create a box if it's always transparent.
- Exposed the Futures on TransitionRoutes.
- Fixed that menus were no longer dismissable by tapping the modal
  barrier.

These end up not actually being used, currently, because we don't have
generic methods, which you'd need for showDialog() and friends, and we
don't have any way to parameterise a class type at runtime, which you'd
need for MaterialApp routes, but it's a step in the right direction.

Shadows now render as three seprate MaskFilter.blur components per the most recent Material spec.

The shadows Map was replaced by a similar Map called elevationToShadow with entries that match the 10 elevations specifed by http://www.google.com/design/spec/what-is-material/elevation-shadows.html.

The "level" property (many classes) is now called "elevation", to match the Material spec.

BoxShadow now includes a spreadRadius parameter - as in CSS box-shadow. Renamed the BoxShadow blur property to blurRadius to further align BoxShadow with CSS box-shadow.

PageRoute is now MaterialPageRoute.

This also changes the following:

- Now the HeroController is a Navigator observer, rather than a feature
  of HeroPageRoutes, which are gone. This means heroes can work between
  any kind of ModalRoute now.

- ModalPageRoute is moved from modal_barrier.dart to routes.dart.

- It allows routes to opt-out of their modal barrier being a shortcut to
  popping the route.

- Features of PageRoute that aren't Material-specific get promoted to
  ModalRoute features: storage, the subtree key, offstageness...

The AnimatedModalBarrier is still a ModalRoute feature.

Previously, we passed widgets up the hierarchy to display them in the overlay,
but that breaks the change propagation logic because those widgets won't get
rebuilt.  Now we pass WidgetBuilders instead, which can be rebuilt when the
overlay rebuilds.

Fixes #1913

This patch introduces the notion of a ModalRoute that puts up a modal barrier
and makes the route invisible to hit testing when its animating out. This patch
also uses this mechanism in a number of places (including PageRoute). There are
still a few more cases to convert, but that's work for a future patch.

Fixes #1684

Previous these callbacks were leaking the implementation detail that they were
triggered by taps. In a later patch, we're going to add a parameter to
GestureTapCallback that these callbacks won't have.

Related to #1807

Now you don't need to pass the navigator around everywhere.

Assert at build time that PageRoute route builders do not return null
widget trees.

Also very minor new code comments and code reorg to help make the heroes
patch easier to review.

(These are changes that are unrelated to Heroes but that were part of
the Heroes patch.)

The goal is to follow the guidelines in
https://github.com/flutter/engine/blob/master/sky/specs/style-guide.md#packages

Fixes #1638

Add type annotations in many places.
Fix some identifiers to have more lint-satisfying names.
Make all operator==s consistent in style.
Reorder some functions for consistency.
Make ParentData no longer dynamic, and fix all the code around that.

Canvas is by far the most popular type of material by call site (and makes for
a faster default because it doesn't have a RRect clip).

These are now part of material.dart.

Also, have dialog buttons use the accent colour.
Also, generally rationalise some of this stuff to match Material better.

This patch prepares us to create routes that control their performances more
closely.

In the vast majority of cases, folks should be interacting with the Widget
rather than its State.

Fixes #267