log: use "hidden" filtering instead of manual check at display time When log is not given the --hidden option, hidden revision are not shown. We move the implementation from manual checking at display time to changelog filtering. This is the first official usage of the hidden filtering.

clfilter: introduces a hidden filter This filter exclude all hidden revision. We plan to use this filter to hide revision instead of manually checking contents of the hidden revisions set.

perftest: allow selection of volatile set to benchmark This helps when you focus on a subset of the volatile chain.

perftest: add a command to benchmark construction of volatile cache Obsolescence and filtering related caches are critical. Having a handy way to check them is valuable.

perftest: add an option to invalidate volatile cache Some revsets are sensitive to such initialization. Being able to test the impact is great.

perftest: document the perfrevset command I'll add an argument to it.

perftest: migrate to new style command declaration Declaring synopsis and argument on the function site is much clearer.

perftest: drop duplicated codes The `perfnodelookup` lookup commands is duplicated. We drop the first version, overwritten by the seconds.