Improve stitching (again ^^)

TODO

• implement a first version of the "image minimum divergence" and "higher signal" algorithms
• check issue with normalization: looks like current normalization is not applied when processing is done remotely ???!!!
• add an interface to provide axis 2 positions
• implement an option to find X relative position from nabu cor algorithm for projections
  • we could either get something in nabu or reuse the existing stuff on tomwer, adding possible input to tomwer axis being a serie and retrieving a dict with {"dataset_id": "cor_value"} which will be must faster.
• add a warning if current normalization cannot be done when stitching projections
• dump stitching configuration into an NXprocess
• add a --datasets options which generate url for the stitching directly

example of providing datasets to the configuration file

nabu-stitching-config --datasets *.nx