Add a vBasecamp achievement. (same as vEveresting)

Just recently a new challenge has been added by Hells500 who run the Everesting challenge. It’s called basecamp and is achieved when 4424 meters have been climbed in a single activity. This has been also promoted by the TBR team on Zwift. Could you please add a Basecamp challenge to Zwift, same as the Everesting one, only achieved at 4424 meters.

Rob (TBR)