Add configurable "start page"

[blammit]

Allow a "start page" to be configured. This is the page that will be shown:

• on application start-up
• after the application is idle for a certain time, as configured in settings

Add a settings page at Settings > Display & Language > Start Page, with these options:

• Start page
  Show this page on application start-up.

  • Auto <-- this is the default selection
    After one minute of inactivity, if the current page is one of the following, then save it as the start page.
  • Brief
  • Brief - side panel open
  • Overview
  • Levels - Tanks
  • Levels - Environment
  • Battery overview

• Timeout
  Revert to the start page when the application has been idle for this duration.

  • Never <-- this is the default selection
  • 1 minute
  • 5 minutes
  • 10 minutes
  • 30 minutes
  • 60 minutes

[blammit]

Added "blocked" label, pending some settings to store these values, e.g. /Settings/Gui/StartPage and /Settings/Gui/StartPageTimeout.

[jhofstee]

I added them as /Settings/Gui2/StartPage /Settings/Gui2/StartPageTimeout so that it is clear they belong to gui-v2 only.

[blammit]

Thanks, removing blocked status.