default output validator error margin

[RagnarGrootKoerkamp]

In the default output validator, when the float (absolute/relative) error is given as epsilon, we should probably use epsilon * (1 + 0.01) or so in practice, to avoid rejecting submissions that are only just below epsilon away from the correct answer.

We should also check what the DOMjudge/Kattis default output validators do and make this consistent maybe.

[mzuenni]

right now we should be identical to domjudge

[mpsijm]

For reference: that's this file, but it looks like this has been updated since we last synced:

https://github.com/DOMjudge/domjudge/blob/main/sql/files/defaultdata/compare/compare.cc

DOMjudge also does not have an extra "error on top of the allowed error". I think it's fine if we keep it like this, because typical submissions should not get close to the error that we permit anyway – this only matters for the jury submissions that very crudely add a constant 10¯⁶ on top of the actual answer for the purpose of testing the validator.