Aligned tiling does not work in general nD with partial updates

[Dimitar Misev]

Aligned tiling in general works by tiling the data that is inserted in a single request (insert or update), and does not try to conform this to the global tiling schema.

Suppose there is an object with aligned tiling 10x10x10. Updating this object with a 3D cube of 100 x 100 x 100 will tile the cube properly into 10x10x10 tiles. Updating it with 100 2D images however will result in each tile being 1x10x10, because each 2D image is tiled independently of the others, and the tiles are not merged in order to conform to the global tile scheme of 10x10x10.

This is a tough problem to solve. The workaround for now is to use regular tiling (with the default rpt_index). To improve performance of import with regular tiling please see wiki:Performance#Tilecache