removed unused code, fixed COCO export issues (ellipse rotation angle may not be available, supercategory now correctly refers to the region attribute name, moved category adding code out of the loop to avoid adding a large number of duplicate categories)
removed unused code, fixed COCO export issues (ellipse rotation angle may not be available, supercategory now correctly refers to the region attribute name, moved category adding code out of the loop to avoid adding a large number of duplicate categories)

ox-vgg/via,ox-vgg/via,ox-vgg/via,ox-vgg/via,ox-vgg/via,ox-vgg/via