LibGfx: Handle filling complex shapes better

This allows the painter to render filled complex shapes better, by
constructing a path graph for (interesting) intersecting lines and
omitting lines from the containing segments if they are detected
to take no part in defining the edges of a shape.

This approach would still fail if there are multiple logical shapes
that are confined to the collection of lines.
For instance, two polygons intersecting each other in a way that one
vertex of polygon A ends up inside polygon B.
we would detect that polygon A's edges are part of the shape
(technically correct) even though they are not a part of polygon B at
all.

Libraries/LibGfx/Painter.cpp

@@ -1154,7 +1154,7 @@ void Painter::stroke_path(const Path& path, Color color, int thickness)
 
 void Painter::fill_path(Path& path, Color color, WindingRule winding_rule)
 {
-    const auto& segments = path.split_lines();
+    const auto& segments = path.split_lines(Path::Simple);
 
     if (segments.size() == 0)
         return;