use Aspect.Fill to measure images. also make sure we do not crash if the
Bounds are smaller than the request. Like any other control, we will
draw outside of our bounds, and rely on ClipToBounds for a nice shave.
* [C] FlexLayout, with managed engine
* [C] add type converter and attributes for CSS
* [C] fix flex-order
* [C] fix typo and margin in Flex
* [Flex] relative value for Basis, padding on the layout
* fix docs
* [Flex] fix NRE on empty layout
* [flex] fix layout measuring
Stephane Delcroix
Rui Marinho
Jason Smith
Daniel Cazzulino