Aerobic TISS fixup

.. for rides with samples other than 1s recording.
Fix AllPlot SEGV on Compare

.. introduced by a dodgy cut and paste to support the new
   data series Aerobic TISS.
Mouse Over Interval List to Highlight

.. same as hovering over the interval in the ride view
   hovering over it in the tree list now triggers the
   event.
Clear Compare Pane

.. last piece of the jigsaw for compare mode. This update adds a
   clear button to the compare pane bar.

.. we can still add lots more to compare mode, but for v3.1 this
   is probably enough now, so closing the feature request too.

Fixes #343.
QT Mac support is shit

.. making our own buttons to get around the hideous pile of shit
   that is a QPushButton on Mac when you want it to be smaller than
   a billboard sign.
Attempt to fix aPower calculation
CP plot ride as %age of best

.. to quantify the areas trained during the ride
CP pointHover

.. plot the interval on hover in the sidebar.
CP pointHover fixup

.. bounds checking on array index
.. set curve grey not white!
More CP plot fixups

.. allplot color fixed when not a rainbow curve

.. fix SEGV index bounds check off by one

.. hover curve z-order to top
Remove errant qDebug statements
More CP fixups

.. hover curve clear on new ride

.. fix ride plot mode so when plotting ride it always
   does. This was fixed by initialising ridePlotMode in
   the CpintPlot constructor.
Rename LTM to Metric Trends

.. LTM is a meaningless acronym
PfPv dots brush

.. been meaning to do this for AGES. the dots in the PfPv
   chart are now filled rather than hollow.
Implement Interval Hover in PfPv

.. only from interval list
.. need to also implement from chart hover too
PfPv fixups

.. hide hover curve when change ride
Bit of transparency on PfPv

.. so we can see overlapping intervals.
Fix SEGV in Histogram when clearing compare

.. because the arrays were emptied!
Fix CP scale for percent

.. when showing the ride as a percentage of bests on the CP
   chart we need to adjust the scale when its > 100%.

.. this can happen when comparing a ride with a bests chart
   for a period the ride was not part of; e.g. todays really
   strong ride vs my bests for the beginning of the year.
Add Interval Markers to PfPv

.. mark the center of an interval (i.e. the average aepf/cpv
   for that particular interval).

.. this is in preparation for mouse over the interval causing it
   to be highlighted on hover.