Don't reset ANT channel settings on search timeout

Wiping out these settings prevents a successful reconnection
of the device if it comes back into range

Fixes #514
Merge pull request #731 from dresco/ANT

Don't reset ANT channel settings on search timeout
Show reference lines on CP chart

.. but only when showing a 'power' data series
   such as NP, xPower, aPower etc.
Merge branch 'master' of github.com:GoldenCheetah/GoldenCheetah