make zeo++ and eqeq checks optional

[kjappelbaum]

The intuition being that they (especially the zeo++ check) are not "basic" sanity checks.

Not sure yet how a good API for this would look like. We could add the kwargs for zeo++/eqeq in the class initialization which default to false. This approach would be an issue if we were to add more kwargs, e.g., for more non-basic checks