[layout] Remove redundant getChildLandAndFrame() method
[layouts] Fix lane lookup logic in Lanes
[layouts] Use same lane lookup logic on both staggered and spannable grids
[layouts] Simplify get(Width|Height)Used() in BaseLayoutManager
[layouts] Add missing 'final' on local variable in SpannableGridLayoutManager
[layouts] Implement lane span support in StaggeredGridLayoutManager
[layouts] Introduce the notion of anchor lane in ItemEntry
[layout] Rename loop variable for consistency
[layouts] Change Lanes.pushChildFrame() to return lane margin
[layouts] Rename childFrame arguments to outRect in Lanes
[layouts] Get rid of getChildLaneAndFrame() in BaseLayoutManager
[layouts] Move getLaneSpanFor*() to BaseLayoutManager API
[layouts] Consolidate measureChild()/layoutChild() into BaseLayoutManager
[layouts] Properly handle span margins in all layouts
[layouts] Make moveLayoutToPosition() abstract in BaseLayoutManager