Support for RTL languages

[moxie0]

In RTL languages, the first item in a grid list would be in the top right. Currently, with StickyHeaderGridLayoutManager it's always in the top left.

The standard GridLayoutManager allows you to specify RTL layout, for RTL language support. It'd be great if StickyHeaderGridLayoutManager allowed you to do the same.

[Codewaves]

I will implement RTL support in the near future.