Add timing info for benchmarks

[d3v-null]

it would be nice to get timing info for benchmarks, like in Birli

init duration: 333.59013ms
read duration: 2.098104748s
write duration: 49.329457162s
total duration: 51.76115204s

DP3 does it too

Total DP3 time     183288 real      330819 user     42425.6 system
    0.0% (   14  s) MsReader
  100.0% (183256  s) GainCal gaincal.
           97.3% (178355  s) of it spent in predict
            0.0% (   76  s) of it spent in reordering visibility data
            2.6% ( 4771  s) of it spent in estimating gains and computing residuals
            0.0% (   12 ms) of it spent in writing gain solutions to disk
        Converged: 1, stalled: 51, non converged: 8, failed: 0
        Iters converged: 0, stalled: 23, non converged: 300, failed: 0
    0.0% (   32  s) Averager averager.
    0.0% ( 1039 ms) MSWriter msout.
      0.0% (    0 ms) Creating task
    504.4% ( 5241 ms) Writing (threaded)