Fracture Voronoi

v1.0: The object is broken in a number of chunks equal to 'Nb Parts' to the power of 'Iterations', using Voronoi cells. The final number appears on the 'Break' button.
The creation process is visible in the viewport.
For a similar result, it is faster to use several iterations with a small number of parts than creating all the parts in one iteration.
Note that the original object is just hidden, not deleted.

v1.1: In this version, the code has been improved and runs much faster. But there is no viewport feedback any more.
Materials:
- the outer faces keep their original material IDs and the new faces are assigned a unique ID. The value that appears by default is the highest ID in use (by the original object) + 1.
- mapping coordinates (if any) are preserved and somehow 'projected' onto the new faces.
- an extra planar mapping is applied to all the pieces at once and set on its own channel, typically for use with 3D procedural maps, so the pattern flows continuously from piece to piece but sticks to them when they are moved apart.
Hierarchy:
- when using several iterations, it is possible to keep the intermediate generations of parts.
- when linked, each part is parented to the one it is derived from.
- generations are set on their own layers, which are hidden except for the last one.

Enjoy :)