There are a lot of class methods. Do we need this? If I remember correctly, I first used them in the old reconstruction to be able to call a few methods without instantiating the class. Instantiation was not fun, because you needed to specify datafiles, groups, and whatever. Now, however, we're building mean-and-lean classes which can be instantiated at no cost, they don't even have an `__init__` method! So, the difference between class methods and regular methods is:
```python
DirectAlgorithm.reconstruct_common(t0, t1, t2, x0, x1, x2, y0, y1, y2)     # classmethod
DirectAlgorithm().reconstruct_common(t0, t1, t2, x0, x1, x2, y0, y1, y2)     # regular method
```
Right? Maybe I'm missing something.