PyNutil only worked for method = "all". Fix so that it works for "per_pixel" and "per_object".

The reports now give same region pixels as Nutil

fixed issue where PyNutil would fail on sections that have 0 pixels, or where min object size was set too high

Slice reports and whole series reports now correct

There is an error in the combined_report (it sums the area_fraction).

per_section_meshview
per_section_reports
sections_combined_meshview
sections_combined_report