Added virtual power support for Tacx Blue Twist trainer
Added virtual power support for Tacx Blue Motion trainer
added Tacx Blue Twist and Tacx Blue Motion to Device Wizard
Histogram Compare Axis Scaling Fixup

.. truncate the x-axis for small values

.. only set y-axis max for selected intervals
Histogram Compare Fixup

.. remember we can plot for a season and recognise that
   when checking for isCompareIntervals in PowerHist.

.. fixes a SEGV when looking at a histogram in the trends
   view whilst compare intervals is active in ride view.
Compare Pane Don't Add Metrics already there

.. distance and duration are default metrics on the
   summary, so we need to make sure we don't double
   up on the compare pane.
Compare RideFileCache Optimisation

.. need to only create when needed and also need to
   delete when done.
Golden Ratio for Grouped Bars

.. on the histogram charts when comparing multiple
   intervals we group using a golden ratio to make
   it easier to read.

.. this is less about the histogram and more about
   establishing the aesthetic in time for the LTM
   updates for compare date ranges.
HistogramWindow remove legend

.. for now, it causes a nasty refresh glitch.
Fixup compare interval refresh

.. usual signals and refresh optimization and
   bugs (switch tabs + switch compare mode).
Fixup Histogram Compare Zones

.. it was using the range from rideitem
Merge pull request #737 from Tafkas/master

Add virtual power support for Tacx Blue Twist and Blue Motion trainers
Merge branch 'master' of github.com:/GoldenCheetah/GoldenCheetah
merge upstream into master