stringutil: promote smartset.prettyformat() to utility function It will be used by debugwalk.

profiling: introduce a "profiling.time-track" option This option allows to switch the time used by the statistical profiler from cpu to real time. Our goal is to profile IO intensive operations using the mercurial profiler.

statprof: also gather wall time Gathering wall time information is useful for operations that are IO (files, network) intensive. For now we only expose it in the final summary.

perftemplating: allow to specify the template to test This is useful to test the evolution of rendering time for a given template.

perftemplating: stop going through the log command Only benchmark the rendering phase by moving steps outside of the timed function: * revisions resolution, * template parsing

perftemplating: move revision argument to flag only The revision we want to render are less important than the templates. We move revision specification behind the usual `--rev` flag.

perftemplating: drop usage of buffer The buffer can consume a lot of memory and change various internal behaviors. Writing to dev/null seems more appropriate when it comes to benchmark.

perftemplating: move template formating into its own function The lambda is not practical when time will come to alter the benchmark code.

perftemplating: fix the revisions argument Before this change, the argument passed to log where a string instead of a list of string. This meant only single character rev were supported... We now properly accepts argument of any length. We also make it possible to specify multiple REV arguments in the same go.

py3: make sure util.username() always returns bytes Differential Revision: https://phab.mercurial-scm.org/D3706