Move tests to top level directory

.. they don't belong in the src directory!
Fix RidePlot draw performance

.. by only plotting the stack view if its actually
   needed (i.e. user has selected stack view).

.. this performance degradation was introduced by the
   axisscaling update (which is a nice update)

Fixes #616.
UI Nits: AllPlot interval too hard to see

.. the interval highlighter is so feint that it can hardly
   be seen -- increased the alpha from 64 to 128.
Documentation: Withings setup in FAQ

.. to explain where to get the user id and public key
   from (it foxed me for a while).
Documentation: How to create/edit Seasons/Events

.. added to the FAQ for v3.0.
BinRideFile: Support for left-right pedal balance

Test ride file : test/rides/2013_05_15_18_38_30.bin