- Ifc: fine-tune some epsilons.
- Ifc: add heuristic to detect remaining, unwanted "crossing caps" and to drop them silently. Testing this on some larger files, it typically reduces artifacts due to z-fighting on lower window caps.
- Ifc: refactor border detection code.
- Ifc: fine-tune epsilons. Correct epsilon approximation for a squared value is max(e^2 +- 2e).