charts: fixed x axis data format does not work well with short periods

[micw]

Expected Behavior

x axis text should adapt to the interval or be configurable

Current Behavior

x axis has fixed day/month text

Possible Solution

• decide based on interval
• make it configurable

Steps to Reproduce

render a chart with a 12h intervall

Context

render a chart with a 12h intervall

Your Environment

• Version used: master

Screenshots

[micw]

Related to #388
@maurerle