Added AutoRotateStackLayout

[nbadakh]

- The AutoRotateStackLayout displays its contents along the horizontal axis by default. - If the contents do not fit along the horizontal axis, the AutoRotateStackLayout switchs to displaying them along the vertical axis. - The AutoRotateStackLayout uses to StackLayouts to implement its behavior. - Also added AutoRotateStackViewController to demonstrate the use of AutoRotateStackLayout. TODO: Add tests.

[nbadakh]

- Attached screenshots:

[FabianTerhorst]

This would be the first none essential layout that would go into the library. Wouldn't it make more sense to split it in an sub project?

[nbadakh]

Added unit tests

[staguer]

@FabianTerhorst you bring up a good point, thank you, we'll consider it.

[nbadakh]

Fixed merge conflicts.

[staguer]

@FabianTerhorst We're considering generalizing this component a bit. It would take an array of layout options and at measurement time it would pick the first one that fits. Sounds like a useful primitive for apps that need to support Dynamic Type and languages with long words. What do you think?

[FabianTerhorst]

Sounds good.