The DisplayApp class isn't used in the Screen base class and most
screens, so requiring it is pointless.
In this commit, DisplayApp pointers were added to screens which use it
and the explicit Screen constructor was removed in those screens.
Replace separate SettingSetDate and SettingSetTime with a combined screenlist.
Add DotIndicators. Similar to PageIndicator, but for use when separating screens instead of pages of a list.
Co-authored-by: Riku Isokoski <riksu9000@gmail.com>