Add Running Pace Zones (1 of 3)

.. in this first part we just add the pace.zones file
   and basic configuration of critical velocity history
   in the configuration pane.

.. in part 2 we need to fixup custom zones and consider
   how they might be adjusted for VDOT/Daniels etc etc

.. in part 3 we need to add pace zones to the ridefile
   cache and then histogram and summary charts.
Copyright messages in PaceZones

.. in truth the code is largely a copy of Zones.{cpp,h}
   written by Sean, but it seemed a bit odd to not show
   that I introduced the file and the changes.

.. recognising that it doesn't /really/ matter much at all !