Add a display of a roofs for building

[superyasha2]

Add a rendering of the roofs, which are marks with the roof:shape tag. Also roof:levels tag could be used to determine the roof height because it can be different, like building:levels tag is used for marking building levels without roof and sets the height.

And there are some problems. Some roof shapes have a double meaning. roof:shape=saltbox can be interpreted in different ways:

I think you should display this roof type as on the second option because most of the edits to mark the roof type are made with StreetComplete (not sure), which shows the second form. By the way F4Map doesn't render this roof shape at all.

[biodranik]

Thanks! I've created an issue here: #2204