UI: new icon set by Andrzej Ambroz.

This is a monochrome icon set, with a more modern look and icons for
various features that did not have a proper icon before.

source/blender/makesrna/intern/rna_ID.c

@@ -83,7 +83,7 @@ const EnumPropertyItem rna_enum_id_type_items[] = {
 	{ID_TE, "TEXTURE", ICON_TEXTURE_DATA, "Texture", ""},
 	{ID_WM, "WINDOWMANAGER", ICON_FULLSCREEN, "Window Manager", ""},
 	{ID_WO, "WORLD", ICON_WORLD_DATA, "World", ""},
-	{ID_WS, "WORKSPACE", ICON_SPLITSCREEN, "Workspace", ""},
+	{ID_WS, "WORKSPACE", ICON_WORKSPACE, "Workspace", ""},
 	{0, NULL, 0, NULL, NULL}
 };