Minor change to handle how duplicate records in tcx files are handled.
This allows for power and cadence to be properly displayed for rides
with no distance information (e.g. trainer rides).
RideFile data points now include lon and lat members for the longitude
degrees and latitute degrees from the source ride files. As a result
most of the RideFile readers now set longitude and latitude to zero for
each data point, except for:
* Gc Format Files - now support read/write
* Wko Format Files - now support read
* Tcx Format Files - now support read (smoothed if smart recording)
Although there are no features within GC at this point in time that use
positioning data this may change over time. Critically, as users save
files to the new GC file format whilst adding interval data it is
important that this positioning data is not discarded before new
features arrive.
The recording interval can vary. If the recording interval is not 1
second, then the data is linearly interpolated for the time period at
1 second intervals. This allows for smart recording or garmin 705 data
drops to work correctly with GC.
