GP: Redesign wireframe mode

Now it's possible use the different Wire modes (Single, Object & Random)

Also support for x-ray mode.

For random colors, the name of the object and the name of the layer is used.

Also some parameters cleanup.

release/scripts/startup/bl_ui/properties_object.py

@@ -221,6 +221,7 @@ class OBJECT_PT_display(ObjectButtonsPanel, Panel):
         is_wire = (obj_type in {'CAMERA', 'EMPTY'})
         is_empty_image = (obj_type == 'EMPTY' and obj.empty_display_type == 'IMAGE')
         is_dupli = (obj.instance_type != 'NONE')
+        is_gpencil = (obj_type == 'GPENCIL')
 
         col = flow.column()
         col.prop(obj, "show_name", text="Name")
@@ -262,7 +263,7 @@ class OBJECT_PT_display(ObjectButtonsPanel, Panel):
         row.active = obj.show_bounds or (obj.display_type == 'BOUNDS')
         row.prop(obj, "display_bounds_type", text="")
 
-        if is_geometry or is_empty_image:
+        if is_geometry or is_empty_image or is_gpencil:
             # Only useful with object having faces/materials...
             col = flow.column()
             col.prop(obj, "color")