Fixed some coloring issues, respect color theme on file-viewer background, make file-viewer images rotatable

lib/view/pages/more/roomplan/roomplan.dart

@@ -16,7 +16,7 @@ class Roomplan extends StatelessWidget {
         imageProvider: Image.asset("assets/img/raumplan.jpg").image,
         minScale: 0.5,
         maxScale: 2.0,
-        backgroundDecoration: const BoxDecoration(color: Colors.white60),
+        backgroundDecoration: BoxDecoration(color: Theme.of(context).colorScheme.surface),
       )
     );
   }