Make shown data configurable

[sebastianha]

I would really like to see that I can configure the data shown on the screens.

Example 1 - Main screen: Currently time and km is shown. I would be handy to also show average speed or heart rate information here. There should be enough space in the second row.

Example 2 - Interval screen: Currently on the right there is elevation. It would be handy to change this to e.g. heart rate information (avg/max) or other data.

Example 3 - Graph screens: It could be handy to hide shown graphs, e.g. if you are not interested in elevation.

[dennisguse]

Main screen: Also the activity icon is not that important while recording (at least not for me).

[rgmf]

Interesting idea. I like it.

We could apply something similar than we are doing now for sensor data (dynamically loaded).

I don't like icon on recording either... it's not that important there.