Reconstruct a slice for several with several center of rotations

In some case we want to reconstruct the same slice with several cor values. For now we have to launch n reconstruction and generation of the sinogram is done each time. To speed up we could either:

• full y handle this use case
• create a cache on the sinogram creation and the user would benefit from it if keep his instances of nabu classes
• add a way to get sinogram from nabu process and a function to directly reconstruct from it

• other...