* Add support to move the fab between positions.

* Motion demo for the FAB works between center and end floating.

* Add a Material curve to the offset animation.

* Move the fab position into an object

* Updates to docs

* Updates to docs

* Fix a lint on the bottom sheet type

* Add a ScaffoldGeometry class

* Improve the documentation

* Improve the documentation

* Add a fab motion animator

* Add position and scale animations

* FAB entrance and motion animations work

* Get started on FAB motion

* Make fab animation work properly.

* Change the fab animator to be stored in the state of the scaffold.

* Add a layout test

* Fix spacing being off

* Fix the entrance/exit animation test.

* Add a textDirection to the layout delegate.

* Fix const constructor lint checks

* Add toStrings for the fab positioner/animator

* Add a toString for CurveTween

* Change the fab motion demo icon to a simple add icon.

* Add tests and a custom fab positioner to the demo.

* Do not start the fab's motion animation when the fab is null.

* Adjust the code to pass the new tests.

* Rename for in response to Hans' comment.

* Revert the tabs fab demo

* Use timeDilation, and clean up the animation code a little.

* Clean up the prelayout geometry docs and ctr order

* Cleanup fab transition widget code

* Clean up comments on Scaffold, add cross-references between the two geometries

* Explain the fab motion animation scheduling better

* Add a const to the fab motion demo

* Make the fab animation never jank by keeping track of where to move the fab to in the future.

* Add a default fab positioner constant

* Add space after comma in the demo

* Add boilerplate dartdoc to all const constructors

* Comment improvement

* Rename 'fabSize' to 'floatingActionButtonSize'

* Rename 'fabSize' to 'floatingActionButtonSize'

* Rename 'fabSize' to 'floatingActionButtonSize'

* Clean up the prelayout geometry object's dartdoc

* Clean up the prelayout geometry object's dartdoc

* Remove extraneous comment

* Change possessive uses of Scaffold's to use dartdoc-compatible [Scaffold]'s

* Rename the horizontalFabPadding to an expansion

* Clean up controller cleanup and setState usage

* Animate instead of lerp

* Make the fab position animation use offsets instead of animations

* Streamline the fab motion demo

* Set up the animator to start from a reasonable place when interrupting animations.

* Doc cleanup on the new animation interruption

* Expand some uses of fab and clean up constants

* Expand remaining public uses of fab to floating action button

* Expand remaining public uses of fab to floating action button

* Expand on the documentation for the fab positioner and animator

* Refactor animations to broadcast the position properly.

* Add the ability to turn on and off the fab to the motion demo.

* Remove unused code

* Change the fab animator to animate even when the fab is exitting.

* Remove extra positioner.

* Apps -> Applications in docs

* Explain the scale animation.

* Name the child parameter in the animated builder

* RTL before LTR

* Wrap the AppBar in the example code

* const the fab motion demo name

* Start a test against animation jumps

* Test for jumps in the fab motion animation

* Dont initialize values to null

* Use constants, fix spacing from some of Hans' comments

* Clarify the relationship between fab positioners and prelayout geometries

* Explain the fab animmator a bit better

* Explain the animation progress in the fab animation

* Explain the animation restart better

* Explain the animation restart better

* Explain the prelayout geometry better

* Explain that height is a vertical distance.

* Explain the horizontal fab padding

* Update the scaffold size description to explain what happens when a wild keyboard appears

* Remove print statements

* Update the scaffold geometry with information about it being available at paint time.

* In one step of a transition

* Explain how the top-start fab positioner works

* Explain how the top-start fab positioner works

* Refactor the scaffold layout to just pass a padding instead of a bottom, top, start and end.

* Refactor the scaffold layout to just pass a padding instead of a bottom, top, start and end.

* Action buttons with with custom positioners.

* Add a rotation animation example.

* Use a swap animation to show swapping between two different animations.

* Use a swap animation to show swapping between two different animations.

* Add an example for the size animations.

* 2018 copyright

* Extra empty line

* Return new Scaffold

* Extra blank line fix

* All its contents have been laid out

* Position the fab

* Explain what the scaffold geometry is for.

* Move asserts to different lines

* The scaffoldsize will not

* Initial rename of FabPositioners to FloatingActionButtonLocation

* Rename comments in example to refer to location instead of positioner.

* Rename fabpositioner to location in tests and in the scaffold field

* Finish removing references to positioner in scaffold code.

* Split the fab location and animation out into a separate file.

* Make things more private

* Import foundation instead of meta

* Const curve instead of final.