Relative timeline in the temperature graph

[lixxbox]

Requested feature:

Relative time line in the temperature graph, like "5, 10, 15 mins ago" instead of timestamps.
Alternatively you can simply put it in the tooltip just beside the time.

The timeline should be configurable via the cog icon, so that you can switch quickly between the modes.

Solves the following problem:

Sometimes you want to know how long ago a certain event happened (e.g. heating up) then you don't have to calculate the duration.

Additional information:

echarts xAxis.axisLabel.formatter