[v1.0] Minimize image size

[thequicksort]

Description

Once we're closer to release, it may make sense to take some time to investigate ways of making our final image size smaller.

Ideas

• Remove dependency on Pandas (bonus: over 30% of docker image build time is for Pandas alone, so this would be quite nice)
• Build separate release flavors for internal vs. external classifiers
• Re-work matplotlib import of QT5 (using overlays/package overrides instead of importing QT5 full)