openHarmony 0.5.3

Fix for $.scn.selectedNodes setter/ also fixes crashes in $.scn.exportTemplate() (as far as I can tell)
added oBackdrop.nodes/oBackdrop.parent (for the group that contains the backdrop)
added oNode.usedColors (gets colors used from element/scene palettes based on ids in the drawings)
added oNode.containingBackdrops (gets the backdrops containing this node)
added oBox.contains() to check whether one box is inside another