[evaluation] Homogenize segmentation/classification code; Use more credible constructs (DRY); Fix test units

Revamp tests; Delete outdated; Make common conftest.py; Improve segmentation tests; Allow segmentation tests to run on CI

[libs.segmentation.scripts.evaluate] Only evaluate - leave view to another command; Simplify by using credible package

[tests] Centralize histogram production; Fix tests to only verify existing references and error if not all references are checked

Make code and tests flexible to the use of a pre-processed Montgomery dataset to speed-up testing where possible (closes #74)