The Skiba and Coggan metrics for xPower and NP
respectively can now be plotted on the CP curve.
There are two issues;
* Downsampling of data to 5s samples skews xPower's EWMA
* Setting scale to start at 30mins breaks the x-axis scale engine
Both issues need fixing, since the first skews xPower upwards and
the second suggests that xPower/NP are meaningful for durations
less than 30 minutes.
Fixes#307.
This patch enables more data series to be plotted on a CP plot.
We can now show curves for heartrate, cadence, speed and torque
as well as the original power and energy.
The CP code is refactored into the plotting functions and a new
RideFileCache that precomputes the mean-max as well as distribution
data (for a later patch to show histograms across date ranges).
The code for computing mean-max values has been re-written and
significantly optimised by;
* computing 1s intervals up to 5mins only
* computing 20s intervals for the remainder of the ride
* downsampling data to 5s samples for longer durations
* using a binary file format (cpx) for faster read/aggregation
* using multiple threads
Testing on an old Athlon dual-core showed an increase in performance
over the old cpi code of approximately x20, but since new data series
are now computed it is only x4 faster. Quad/Octo core systems will
show a greater performance increase though.
A new config pane for defining color preferences for chart
curves, shading, background and grid lines et al. Default values
echo the current hard-coded values.
And pay attention to MainWindow::activeTab, such that only the active
tab redraws itself when changing rides. This change really increases
GC's responsiveness when scrolling through the ride list.
This mode is fun because the "CP Curve" is a straight line,
just like in the model:
work = CP * time + AWC
You can also see that the AWC is the y-intercept.
