...instead of a deep walk.

Add material design features to Input

That way folks can customize it if they want (and it makes the code a
bit more self-documenting).

Now the label animates from its inline position to above the text and
the focus highlight grows into place.

RawEditableLine is now responsible for the scrolling behavior, which
removes the need for callbacks between RawEditableLine and Input. It
also fixes a bug whereby the whole Input widget (including its icon)
would scroll when the text got long.

Properly support labels, hints, icons, and custom typography.

This reverts commit ab300634.

Make `flutter list` not crash on linux.

Turns out linux does have an ideviceinstaller package
however it doesn't contain idevice_id or any of the
other tools we use.  Furthermore we don't have
xcrun or the rest of xcode on linux so we can't
manipulate simulators either.

No sense in printing out a warning that ios isn't supported
every time on linux, so I wrapped that block in osx only.

@chinmaygarde @devoncarew

Add the ability to lose focus

Fixes #1308

Input widget shrinks when typing a space

This patch restructures how we size the editing region of the Input widget. Now
RenderEditableLine understands that it's a single-line editing widget and sizes
itself correctly.

Simplify colorizing icons

Now you can colorize an Icon simply by proving a Color for the Icon.

Refactor device.dart

remove device type specific checks

'flutter apk' now supports dynamically registered services.

Third-party libraries can now provide their own mojo services. They do
so by adding a config.yaml file to their pub package which contains
- a list of service names and java classes which handles that service's
  registration.
- a list of pre-built .jar files to statically link with the app's shell
  when building the app.

Change Block children to be a named parameter

This is a backwards incompatible change.

Added TwoLevelList et al, a Material Expand/Collapse List Control

A TwoLevelList can can contain TwoLevelListItems, essentially ordinary list items, or TwoLevelSublists which have a list of items of their own. Tapping on a TwoLevelSublist causes it to expand, showing its items. Tapping again causes it to collapse.

Scroll focused input widgets into view

Add device pixel ratio to MediaQuery

When opening the keyboard or focusing an input widget, we should scroll the
widget into view so that the user can see what they're typing.

Don't autofocus Input widgets by default

Remove unused close method from AssetBundle

Instead, require the developer to opt-in to autofocusing because autofocusing
can be disruptive.

Fixes #1307

Scaffold should respect window.padding.bottom

The space for the keyboard is now represented as bottom padding for the window.
By teaching the scaffold to respect the bottom window padding, we move the
floating action button and snackbars out of the way of the keyboard.

This currently works on Android. I'll need to see how to get the keyboard
geometry on iOS for a similar effect.

Fixes #103

refactor commands to move out re-usable functionality

Move scroll_behavior into widgets