Fix/minorbugs

[swinkelmann]

Fixes some minor bugs:

• Missing dialog title in POI dialog
• don't drag a draggable zoombar outside the screen
• change helptext popover (backend security) behaviour ->trigger on hover instead of click so it closes automatically
• german translation for 'dimension' in layertree config

[astroidex]

• OK Missing dialog title in POI dialog
• ERROR don't drag a draggable zoombar outside the screen -> when you move the toolbar to the bottom the rest of the applications (sidepane, overview) moves upwards
• change helptext popover (backend security) behaviour ->trigger on hover instead of click so it closes automatically
  • OK as it hides on close (but dialog does not show up on hover)
• OK german translation for 'dimension' in layertree config