This normalizes all of the "See also" blocks in comments so that they conform in style.

They all look like this now:

  /// See also:
  ///
  ///  * [MyFavoriteWidget], because it's cool.
  class Foo {}

I removed some useless "See also" blocks, and added commentary to ones that were just "bare" references.

This is my penance for adding so many bullets that are "-" instead of "*". :-)

This adds actions and shortcuts arguments to WidgetsApp (and MaterialApp and CupertinoApp) to allow developers to override the default mappings on an application, and to allow for a more complex definition of the default mappings.

I've stopped using SelectAction here, in favor of using ActivateAction for all activations, but haven't removed it, to avoid a breaking change, and to allow a common base class for these types of actions. This is because some platforms use the same mapping (web) for both kinds of activations (both select and activate).

* Update project.pbxproj files to say Flutter rather than Chromium

Also, the templates now have an empty organization so that we don't cause people to give their apps a Flutter copyright.

* Update the copyright notice checker to require a standard notice on all files

* Update copyrights on Dart files. (This was a mechanical commit.)

* Fix weird license headers on Dart files that deviate from our conventions; relicense Shrine.

Some were already marked "The Flutter Authors", not clear why. Their
dates have been normalized. Some were missing the blank line after the
license. Some were randomly different in trivial ways for no apparent
reason (e.g. missing the trailing period).

* Clean up the copyrights in non-Dart files. (Manual edits.)

Also, make sure templates don't have copyrights.

* Fix some more ORGANIZATIONNAMEs

This PR adds TargetPlatform.macOS to the TargetPlatform enum. This allows us to begin implementation of some adaptive UI based on which target platform is desired.

I haven't updated the tests here, that will come in a follow-up PR.

Added support for a themeMode property to the MaterialApp to control
how the light or dark theme is selected.

Fix MaterialApp's _navigatorObserver so it doesn't cause WidgetApp's assertion to fail when using custom navigator, fixes #18904

Fix the spelling errors in the dartdocs for the framework.

There are no functionality changes here, just documentation fixes.

New locale resolution algorithm to use full preferred locale list, include scriptCode in Locale. (#23583)

* Refactor of cupertino/material/widgets app

* update docs 

* Update tests for const

This reverts commit 61cf946b.

* Make CupertinoApp and MaterialApp both use WidgetsApp for Navigator

* Make CupertinoApp and MaterialApp const constructors

* Make WidgetsApp routes aware

* Update tests

* enable lint unnecessary_new

* fix tests

* fix tests

* fix tests

* lint unnecessary_new on samples

* fix tests

It was causing problems rolling Flutter into Fuchsia

* re-enable lint unnecessary_const

* remove trailling whitespaces

* remove unnecessary const (after merge)

This reverts commit cc1cf13e.

This is not a grand refactor yet, it's just cleaning up what we have
already, so that people who keep using this API (e.g. dialogs) have
something coherent to deal with.

The major changes are that Navigator and NavigatorState have the same
API now, that most of the examples use `<void>` instead of `<Null>`,
that the navigator observer can see replaces, and that the `settings`
is moved from ModalRoute to Route. I also cleaned up some of the API
documentation.

This moves toward more consistency in our messaging. Apps are
launched using --debug, so the banner will reflect the build
mode.

For example, so that the gallery can override the media query globally.

This lets people poke at navigators without having to get their
BuildContext from a build function or State first.