GitLab

* support PN2 decode head

* add mmseg dependency in github workflow

* complete PN2 decode head

* modify backbone pn2 to support seg task & its unit test

* add unit test for PN2 decode_head

* remove registry.py in datasets/

* remove registry.py in ops/pointnet_modules/

* remove registry.py in models/

* refactor builder using mmcv.MODELS registry

* update mmcv min version requirement

* change min mmcv version requirement in mmdet3d/__init__.py

* min mmcv version to 1.3.2