ENH: Add interface for diagnostic plotting of intermediate steps

[stefanches7]

As many of us know, it is very helpful to do "sanity checks" of the in-between steps to figure out where and what went wrong in the pipeline. This PR adds visual diagnostic plots to Connectome Mapper that is built in as a nipype interface.

Enhancement ideas:

• [ ] Add connectivity plots
• [ ] Add HTML page where all of the plots are combined
• [ ] Add more interactive / 3D visualizations

[sebastientourbier]

Hi @stefanches7! I was thinking maybe it would be wise to develop this as a separate tool that we could call for instance connectomemapper3_reporter. Thus, this would make the development and maintenance of this part much more efficient. I thinks it should be possible to design it in a generic way that it could handle not only the connectomemapper3 outputs but also the outputs of other BIDS Apps. We could think of specifying the different BIDS derivatives files using a dictionary of dictionaries which can then be provided to pybids.get(). This could be easily store and load to / from a JSON file . WDYT?

[stefanches7]

I have just found Brainstorm and it looks like it's a very versatile tool with lots of functionality. They also have coregistration and all that stuff. Maybe, we can reuse their code @sebastientourbier ?