Moo-ify
Merge branch 'feature/moo'
Update timer docs
Update Changes
Release v0.20

  * Use Moo. This makes the code a little more manageable and has a
    negligible impact on speed.
  * Don't run failure-prone "live" tests on install or CPANtesters, add a
    set of non-live tests.
  * Add the ability to re-target the metric of a timer between starting and
    finishing it.