Update README.md

Merge pull request #91 from raphaelsulzer/python_package

fixed all imports

fixed remaining imports and update readme

made a python package out of the code

Support PyTorch2ONNX and ONNX2TRT for PointPillars

Add demo data for simpler testing && Fix some numpy usage

Create LICENSE

Update README.md

fix bugs [occured in different environments]

add zhihu link

init repo