Improve FeatureSet Tests

[tibuch]

Test and improve FeatureSets.

• [x] 2D Geometric
• [x] 3D Geometric
• [x] Statistic
• [x] Haralick
• [x] Tamura 2D (already has tests)
• [x] Zernike
• [x] Histogram (already has tests)
• [ ] ImageMoments (https://github.com/imagej/imagej-ops/pull/301)
• [ ] Pixel based geometric features

[tibuch]

@ctrueden and @dietzc why do we have expensive geom tests and normal ones?

[dietzc]

I think for historical reasons. If you find "normal" ones which cover all the cases, it's absolutely OK.

[ctrueden]

@tibuch I thought you were the one who authored those expensive tests! No?

I would much rather have only fast-running tests but which still exercise the algorithms sufficiently. But my understanding was that someone (you? someone else?) thought the small ones might not be rich/complex enough to fully exercise the algorithms?

[tibuch]

@ctrueden I guess the tests were added by @seebacherd.

I will replace the images by smaller but complexer (curves, holes and so on) ones.

I would say the accuracy of the tests depends a lot more on small epsilons.

[ctrueden]

@tibuch Thanks, sounds great!