branch, merge

As a part of performance improvements to  StickyGridHeaders  the adaptable-row-height feature has been removed. This means the vanilla GridView behaviour for row height determination has returned and you will have to extend or wrap your own item views in your adapter yourself to change it. The rationale behind this removal is that the adaptable-row-heights feature significantly impacts performance and isn't required in all use cases.

I am looking at making some major changes for StickyGridHeaders. Some problems I want to address are: Headers not being a part of the view hierarchy. Adapter complexity. Navigation issues, especially on the TV platform. At the moment the headers are a visual element only as they are merely drawn into the window after the underlying GridView has been drawn. I have a few ideas on how to fix this. Any fix made will include stickied headers too. I am not sure the navigation issues ('3') can be fixed without a complete reimplementation of GridView. It is possible a solution to the view hierarchy problem ('1') may coincidentally fix '3'. Addressing the adapter complexity ('2') will require some thought, I don't want to change things too much. At the least I'll go through the code and make sure the API is properly documented. Actually, that brings me to the final thing, documentation. At the moment the wiki is unused, once the programm