Unify output for all tilers

[vfdev-5]

Idea is to have unified interface for all tilers:
Currently

ConstSizeTiles.__getitem__ -> x_tile_offset, y_tile_offset, x_tile_extent, y_tile_extent

and

ConstStrideTiles.__getitem__ -> (x_offset, y_offset, x_extent, y_extent), (x_out_size, y_out_size)

and it would be better to have

...Tiles.__getitem__ -> (x_offset, y_offset, x_extent, y_extent), (x_out_size, y_out_size)