stringutil: fix prettyrepr() to not orphan foo=<...> line

debugwalk: pretty-print nested matcher While porting filesets to composition of matchers, I found the original one-liner was hard to read.

debugwalk: show matcher output only if -v/--verbose And drop "egrep -v". This matches the behavior of "hg debugrevspec".

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.