Non-robust interval equality checks

[avullo]

Current implementation based on float comparison, which is fine for genomic coordinates but not good with e.g. time or more precise intervals. Will have to make some experimentation with possible solutions and choose the most stable/robust one.

Good starting points:

• http://www.floating-point-gui.de/errors/comparison
• https://stackoverflow.com/questions/5989191/compare-two-floats

We could start with the simplest approach of using an epsilon (dynamically adjusted maybe) and compare it with the absolute difference.