Tiled view

[tpietzsch]

This is another attempt at (part of) #179 (#306).

It adds Views.tile(...) method to split a RAI into tiles, with the result represented as RAI<RAI>.

Used along these lines:

RandomAccessibleInterval<T> img;
Iterable<RandomAccessibleInterval<T>> tiles = Views.iterable( Views.tiles( img, 32, 32 ) );
tiles.forEach( tile -> op( tile ) );

This is implemented as

• a new class Grid (which is similar to CellGrid, but a bit more general) that splits a interval into regular grid cells, which can be accessed as RandomAccessibleInterval<Interval>,
• Views.intervals(RA<T>, RAI<Interval>) which takes such a RAI<Interval and splits a RA<T> accordingly.

These parts are hopefully independently useful. For example Views.intervals(RA<T>, RAI<Interval>) can also be used to implement tiling with overlap, etc...