Final report implementation

[pierrethibault]

Implemented basic reporting structure (report will appear in ptyr file).

Next steps:

• implement function that evaluates probe area and linear size
• function that calculate average step size
• linear overlap
• area overlap
• oversampling
• fluence map
• coverage map
• transmission map (multiplied with the object transmission)
• summary of other existing metrics (field of view, number of scan points, ...)

All this information is stored in a dictionary called Ptycho.report, and saved in the ptyd file under content/report. We also need a utility that formats the information for easy consultation

• markdown template
• utility to generate the report and figures

This closes #585