Automatic user TZ detection
Added FallbackTZ to activities - populated with user's TZ when available, used when there is no location info to query TZ against.
Removed all exclusions for stationary activities, fixed Strava so it can "download" said activities.
Fixed endomondo static upload
New ActivityStatistics/ActivityStatistic models
Endomondo changes to support stationary activity stats
Strava manually entered activity listing + "downloading,"
No more UploadedTo, replaced with ServiceData/ServiceDataCollection
RK stationary activity stuff
Added SportTracks statistics, changed Stats.Distance/MovingTime/Distance to use ActivityStatistic
Activity statistic coalescing + tests for that & unit conversions
Coalesce activity statistics when accumulating activities, misc cleanup
TCX stationary statistic export.
Don't set default TZ when substituting user.
Rearranged supplemental statistic calculation into its own file.
FIT activity file generation
Switched GC, Strava to FIT upload
Garmin Connect activity stats download
Fix for FIT distance being 100x off, added proper sport/sub_sport field values.
Updated TCXIO to accept TCX files with no path.