option to display/hide place fill color

[Klumbumbus]

Admin boundaries are always multipolygons and use the key place=*. This leads often to confusing lines crossing the map data because of not fully loaded multipolygons. See screenshot. Furthermore it changes the fill color of other area objects and the aerial backgound imagery. There should be a mappaint setting to display/hide the place fill color.
(The mappaint style coloured streets already hides them always for better view.)

The question is if the fill color should be displayed by default or not. Any opinions?

[Klumbumbus]

In 8986/josm:

fix #12043 - hide place fill colour and add a mappaint user setting to display it again.

[Klumbumbus]

In 13394/josm:

• fix #15648 - warn about unclosed ways with place=islands
• fix #15659, see #12043 - always display place=island and place=islet fill color (and name) independent from the place style setting. Regression of r8986.