added PaintStairs from https://forums.autodesk.com/t5/revit-api-forum/paint-stair-faces/m-p/10388359
added PaintStairs from https://forums.autodesk.com/t5/revit-api-forum/paint-stair-faces/m-p/10388359

jeremytammik/tbc,jeremytammik/tbc,jeremytammik/tbc,jeremytammik/tbc,jeremytammik/tbc