Revert "Revert "JSON char > 127 codepage problem""

This reverts commit 91397851a10739350339743d89467cfa5a38fc24.
New Metrics for MTB - Bike Carrying Time/Elevation Gain

... 2 new metrics (estimates) mainly relevant for MTB or Race bike steep
passes
... a) Time Carrying = moving < 8kph, gaining height, no power, no
cadence
... b) Elevation Gain carring = same criteria, but adding up the
elevation gain

Since there is a certain level of error, the metrics is named as "Est".
Make no video the default

.. in gcconfig.pri

Fixes #1052
Add Last 2 Months to Seasons

.. jump from 38 days to 3 months is a bit much
Add HrPw Metric

.. as a ratio of Average Power to Average Heartrate
   hrpw = ap / ahr
Move heatmap output to Athlete folder