perf: use the new setup function in "perfbookmarks" This command was picked arbitrarily to display the usefulness of the new feature. In my Mercurial repository (with very few bookmarks), moving cache cleanup in the dedicated setup function has a visible and stable effect on the benchmark number. before: ! wall 0.000061 comb 0.000000 user 0.000000 sys 0.000000 (median of 40837) after: ! wall 0.000058 comb 0.000000 user 0.000000 sys 0.000000 (median of 40500)

perf: add a `setup` argument to run code outside of the timed section With this new argument, it is possible to perform special setup and cleanup outside of code actually timed. This is useful to provide more accurate benchmark.

perf: explicitly pass title as a keyword argument in `perfdiffwd` This will help to update the timer function arguments in a later changeset.