Sculpt: Color filter fill mode

This implements a fill mode in the Color Filter tool, which fills the
entire mesh with a specific color.
As this functionality is part of the color filter, this allows to control
the blending of the fill color with the filter strength.

Reviewed By: sergey

Differential Revision: https://developer.blender.org/D8158

release/scripts/startup/bl_ui/space_toolsystem_toolbar.py

@@ -1263,6 +1263,8 @@ class _defs_sculpt:
         def draw_settings(_context, layout, tool):
             props = tool.operator_properties("sculpt.color_filter")
             layout.prop(props, "type", expand=False)
+            if (props.type == "FILL"):
+                layout.prop(props, "fill_color", expand=False)
             layout.prop(props, "strength")
 
         return dict(