Benchmarks: Time::Keeper::Business against its marks, and against the CPAN
modules that do part of what it does where they are installed.

From the dist's top, after `perl Makefile.PL && make`, with Time::Keeper
built beside it or installed:

    perl -Mblib bench/run.pl               # every mark
    perl -Mblib bench/03-plus-days.pl      # one

Each line says PASS or FAIL, our rate and the mark set in
plan_time_keeper_business/00-overview.md (B14) before any number was seen;
a comparison line adds the other module's rate and the ratio. A rate is
calls a second over a fixed CPU time, the best of five.

    TK_BENCH_SECONDS   seconds a run (0.5)
    TK_BENCH_RUNS      runs, the best kept (5)
    TK_BENCH_LOADS     fresh processes for the load time (41)
    TK_BENCH_LIB       directories searched last, for Date::Business,
                       DateTime::BusinessHours, Business::Hours and
                       Date::Holidays, which are never installed in site
