Strava download #14
Description
Add method to download activity as GPX. This is not directly supported by the API, but access to all data is given (as 'streams'). File output can be done using gpxpy. Extensions data (heartrate, cadence, power, ...) are somewhat tricky but I believe I found a way to make them work.
Caveat: I only use Strava for biking, so I may be missing extensions relevant to other activities.
Issues #2 and #3 are depending on this ticket.
PS: it would be nice to be able to save activities as .fit instead of .gpx (extensions are supported more readily, I take it, and files are smaller in size). I didn't see a mature library allowing that, though, and I don't understand the format well enough to develop one myself.