Graphing display span is max 4 hours; ought to be as long as suitable

[rdancer]

The display should be able to visualise for example:

• whole day (16h+) of riding

• whole week (168h) of daily trips

• battery voltage increase when charging overnight (8h+)

• whole month or year of trips or charging cycles (may need some extra storage space, or clever lossy compression, to store data)

• Adapt display resolution to however long the display has been on, or

• Allow user to config the max display in the config menu

• Allow user to config the display value when configuring the display screen

Configuring the display screen -- proposed workflow

1. long-press to enter the screen configuration mode
2. press several times until the graphing view starts blinking
3. press one more time, the timespan of the graphing view starts blinking <-- new proposal
4. press , to adjust the time duration (in hours:minutes) of the graphing view timespan <-- new proposal