Very long activities

[Daniel Besse]

Metrics update fails because of memory limitations (eg: id 4662 on u3).

Possible solutions:

• Improve handling of stops (case for 4662, but wouldn't handle ultra-endurance events)
• Increase step size on long activities (decrease accuracy)
• Increase memory (disponible? cost?)

[Daniel Besse]

List of failings: 4662 u3, 6901 u5, 10380 u9

[Daniel Besse]

Increase memory limit to 512Mb (from 128Mb) and execution time to 60s (from 30s). In addition to several memory improvements in the last commits in MY_StressScore.php