Drag from the right is no more
Longpress is now only 100ms instead of 500
Added optional duration field to longpressgesturerecognizer
Added controller field to material scrollbar api
Haptic feedback only triggers when scrollbar is fully expanded
Added haptic feedback when releasing the scrollbar after dragging it

Vibrate when starting scrollbar dragging.

You can drag the cupertinoscrollbar if you pass an active scrollcontroller to the scrollbar.

- Fixed extentInside calculation in ScrollMetrics
- Added asserts to extentInside getter, as well as ScrollPosition.applyContentDimensions to enforce minScrollExtent <= maxScrollExtent
- Added padding to ScrollbarPainter, updated implementation. Took care of some edge cases.
- Changed some scroll bar constants on Cupertino side.

* Re-enable const

* fix indentof statements in BlockFunctionBody

* fix indentof statements in BlockFunctionBody in tests

* enable lint unnecessary_new

* fix tests

* fix tests

* fix tests

Add minOverscrollLength to make CupertinoScrollbar thumb correct size in long scroll views.

* Create CupertinoScrollbar

* handle main axis margin

* Adaptive material scrollbar and tests

* Small tweaks

* reapply changes on head

* Docs

* start

* Refactored ScrollbarPainter to be more immutable

* fix tests

* fix bug: one animationcontroller pointed to multiple painters

* some docs tweak

* remove unused import

* review

* review

* add dispose