Decide whether benchmarks are necessary

This project has no benchmarks. This has happened by default. It's possible that this is in fact the right choice, because it may be that in practice, any benchmarking involving this library needs to be application-specific. (Performance problems when using this library are more likely to be as a result of the way in which it is used, than with the library itself.)

However, this should be a deliberate decision, rather than an accident. In any case, the IMM currently doesn't provide a way to opt out of benchmarking scores, so we need to decide whether the way we handle this is to award points for "We have positively decided not to do this", or just to make the relevant measure (or even the entire rule) definitions optional.