Fix - Compare Rides-Summary Page: AvgHR, AvgPw,... = 0

... if a metric occurs in more than section (total, avg, maxima,
metrics) the value on the Ride Summary Chart in CompareRides mode
displays "0"
Merge pull request #1015 from Joern-R/pull5

Fix - Compare Rides-Summary Page: AvgHR, AvgPw,... = 0