* add onnxruntime test tool, update pytorch2onnx to support slice export
* onnx convert with custom output shape, update test code
* update pytorch2onnx, add rescale_shape support, add document
* update doc for lint error fixing
* remove cpu flag in ort_test.py
* change class name, fix cuda error
* remote comment
* fix bug of torch2onnx
* mIOU to mIoU
