contrib: add a write microbenchmark to perf.py I'm adding some performance logging to ui.write - this benchmark lets us confirm that the cost of that logging is acceptably low. At this point, the microbenchmark on Linux over SSH shows: ! wall 3.213560 comb 0.410000 user 0.350000 sys 0.060000 (best of 4) while on the Mac locally, it shows: ! wall 0.342325 comb 0.180000 user 0.110000 sys 0.070000 (best of 20)

ui: provide a mechanism to track and log blocked time We want to log the time Mercurial spends trapped in things outside programmatic control. Provide a mechanism to give us both command runtime and as many different sources of blocking as we deem useful.

mercurial: switch to util.timer for all interval timings util.timer is now the best available interval timer, at the expense of not having a known epoch. Let's use it whenever the epoch is irrelevant.

util: introduce timer() As documented for timeit.default_timer, there are better timers available for performance measures on some platforms. These timers don't have a set epoch, and thus are only useful for interval measurements, but have higher resolution, and thus get you a better measurement overall. Use the same selection logic as Python's timeit.default_timer. This is a platform clock on Python 2 and early Python 3, and time.perf_counter on Python 3.3 and later (where time.perf_counter is introduced as the best timer to use).

color: move the '_render_effects' function to the core module

color: move '_effect_str' function into the core module

color: move configstyles into the core module The extension is getting thinner as we speak!

color: rework conditional 'valideffect' Not very important, but the full conditional is not that hard to follow and having it unified make the function role a bit clearer in my opinion.

color: move 'valideffect' function into the core module

color: move '_terminfo_params' into the core 'color' module On step closer to have color in core.