connecting means preferably a removable clip 70 pictured in fig4 42 this clip 70 is preferably a sliding clip and rides along the support arm 13 and engages with the pin or stud 50 this preferred clip 70 may be generally of any shape but it has a first arm 71 and a second arm 72 that are shaped to encircle the pin or stud the arms 71 and 72 are connected by a flat base portion 73 that extends from the arms at one side of the base portion 73 there is a first sidewall 74 extending downwardly and a second sidewall 75 extending from the opposite side of the base portion 73 extending inwardly from each of the flanges 74 and 75 is a retaining means 76 and 77 in operation the support arm 13 is received by the area formed by the underside of the base portion 78 the flanges 74 and 75 and retaining means 76 and 77 see fig4 if this embodiment is used a slot 79 may be cut into the support arm to allow the clip to move between two positions fixed and unfixed a flange 91 extending downward from the clip 70 fits into the slot 79 in the support arm 13 rides along it to move the clip between the fixed and unfixed.