Rename EF to Efficiency Factor.
Fix zero speed in TxtRideFile for Imperial units

When importing files with imperial units the importer
does not set distance data and the speed is reset to
zero.

This patch fixes that.
Remove dynamic load of libusb on Windows

It wasn't adding any value and caused problems
with static build targets and using libusb functions
in other parts of the code (e.g. EzUsb).
Tacx Fortius Driver Stubs

To work with Tacx Fortius on 32/64 bit platforms without
having to install the Tacx software (which requires the
user to pay to upgrade to TTS2/3/4).

Fixes #550.
Fix Histogram Crash

When selecting the speed tab on an imported ride-file, GC exits
with the following error on the command- line: ASSERT failure in
QVector<T>::operator[]: "index out of range", file
/usr/include/qt4/QtCore/qvector.h, line 347.

File: PowerHist.cpp on line 393
low has value -5.55111512312578e-17 which is like -0.0000000000x

This caused an out of bound error on array lookup.

Fixes #551.
Add Virtual Power for 1UP USA bike trainer

Fixes #560.
ANT+ Use Cadence from Standard Power Messages

Standard power messages include an instant cadence
value which we ignored. We should use this if it is
available.

Fixes #556.
List last month, not year for TrainingPeaks.com

By default the TrainingPeaks.com download dialog will
fetch the last year of ride files. This can take a long
time for some users. We now only ask for the last month
by default.

Fixes #561.
Fix Fortius Power Smoothing

Recent fixups introduced a delay of 50ms when
reading from the Fortius controller to avoid
interrupt write errors.

The smoothing of power data was not adjusted to
take into account the reduced frequency of
telemetry updates.

We now smooth at 16hz not 60hz.
remove debug from Fortius.cpp.
Virtual Speed

Tom Compton of AnalyticCycling.com has provided
a formula to calculate virtual speed based upon
slope, weight, power, cdA, crr and air density.

This is now implemented as 'Virtual Speed'.

It is expected that this new virtual speed will
be used to control streetview, video rendering
and future implementations of group riding over
a predefined course.

Fixes #527.
Rolling Average Power/Cadence/HR tweaks

The slider in the controls should only be shown
for HR/Power/Cadence. Additionally, it is more
of a 'smoothing' (rolling) average, so the text
has been changed to reflect that.

This is to avoid confusion with the other series
entitled Average Power. Average Cadence and
Average heart rate - which are averages for the
entire ride.
Fix nan/inf values for Virtual Speed.
Training Dials have own Color setting

For expoediency the training dials used the qwtplotmarker
color but this often lead to things like lap, time being
displayed in black on a black background.

We now have a realtime dials default color setting in the
appearances pane. The default is gray, so will show up on
a black or white background.
CP chart 'best date' doesn't fit

Aside from just expanding the sidebar to show it, this update
creates a bit more space for the display of best values in
the CP chart controls.

It would be better if the tooltip also showed the date.

Fixes #565.
Show date on CP bests tooltip
Fix color array offset broken in commit 3c95f54
Simplify Diary Window

Now only shows monthly view, since;

* qxtscheduleview (weekly) has too many bugs
* rideSummary (ride) is redundant, just add that window to the view

Fixes #546.
Fix Heartrate support for Tacx Fortius

The heartrate value is present in byte 13 of the
received data.

Fixes #555.
Close Window or Quit all Windows

Added a menu option to quit all windows rather than
just the current one.

Each window will process a close event and so give the
user the option to save changed files and cancel closing
it.

Fixes #566.