Use database to save read system info

[D0miH]

Is your feature request related to a problem? Please describe. When changing the appearance of the menu bar items (i.e. changing the width of the menu bar graphs) the information is read on every rerender. This is because the information is read within the update loop of the menu bar items.

Describe the solution you'd like The solution would be to have two independent update loops. One for reading the system information every x seconds while the second update loop updates/rerenders the menu bar items every x seconds. The read system information would be written in a database while when rerendering the menu bar items would read from the database. Another positive side effect of this approach is that the menu bar items could display system information when the app is restarted (i.e. when we maybe want to introduce graphs in later versions)