Changed name to pt2d and remove unnecessary files

pt2d/circleEditorWidget.py

pt2d/circle_edge_kernel.py

pt2d/compute_cost_image.py

pt2d/compute_disk_size.py

pt2d/downscale.py

pt2d/draggableCircleItem.py

pt2d/find_path.py

pt2d/imageGraphicsView.py

pt2d/labeledPointItem.py

pt2d/load_image.py

pt2d/mainWindow.py

pt2d/panZoomGraphicsView.py

pt2d/preprocess_image.py