* roi_extractors: GRoIE addition

Signed-off-by: Leonardo Rossi <leonardo.rossi@unipr.it>

* Fix bug caused by empty tensor and update benchmark results

Co-authored-by: ZwwWayne <wayne.zw@outlook.com>

* Create model file

* Update README.md

* update model url

Co-authored-by: Jiarui XU <xvjiarui0826@gmail.com>

* Update transforms.py

* format with yapf

Co-authored-by: Kai Chen <chenkaidev@gmail.com>

* Deprecate DistOptimizerHook

* Deprecate DistOptimizerHook

* delete DeprecationWarning

* Add resnext x101 32x8d

* Use consistent name

* Use right img norm

* Fix bug in 32x8d backbone

* performance done, links TBD

* fixed vertical flip TTA

* fixed test

* add doc and one more check

* fixed docs

* add dcn offset doc

* move to doc string

* add lvis dataset

* fixed eval

* fixed test cfg

* add resnext config

* update md

* fixed name

* update model urls

* minor fix

* fixed typo

* use open-mmlab lvis

* update travis

* fixed install

* make class balance as default

* Add upsample_cfg support in FPN

* small fix

* Add multiple extra conv sources

* small logical fix

* Add neck tests for fpn

* Add neck tests for fpn

* fixed several typos

* resolved issues

* Removed extra_convs_source option

* added necks to apis.rst

* change according to comments

* add bbox_fields to expand and min iou crop

* reconfigured configs

* small fix

* added test for random crop and min iou random crop

* small change

* added valid_inds for masks in random crop according to #2802

* added config unit test

* deleted nas fpn config test

* revise according to comments

* add img_fields check in transform.py and test_transform.py

* Added notes for random crop and min iou random crop

* Added notes for random crop and min iou random crop

* Add bbox2label and bbox2mask key correspondence

* Update nas-fpn model
Add fsaf log

fixing link typos

* add tutorials

* use arxiv page

* Update links

* clean empty link

* fix a typo

* fix another typo in comment

* add 3x link

* Update model links

* clean scripts

* fix typo

* Add cls weight in CrossEntropyLoss

* update unittes

* resolve comments

* fix unittest bug

* update model_zoo url

* update mmcv version requirement

* fix async test

* minor fix

* Add regression test

* Fix with copy img

* Revert "Fix with copy img"

This reverts commit 86f07e89a400d3cf73464374c7d1ef3d85649c8e.

* Move test to `test_transform`

* fix gcc requirement

* move gcc requirement to install.md

* Implement NAS-FCOS

1. Supports NASFCOS
2. Added NASFCOS_FPN
3. Added NASFCOS_Head
4. Added r50 config

* Revert "Implement NAS-FCOS"

This reverts commit ebae11cbbdc5b4f3cc7226c763e9254c94a9c92b.

* Revert "Revert "Implement NAS-FCOS""

This reverts commit 32bca597859a447de62ddf0f2c2f482809730da9.

* Implement NASFCOS

1. Supports NASFCOS
2. Added NASFCOS_FPN
3. Added NASFCOS_Head
4. Added r50 config

* reformatted & use list to build convs in head

1. code refornatted
2. add docstring in nasfcos_head.py
3. use a list of conv config to build convs, rather than names

* cells merged

1. merge cells in nasfpn ans nasfcos_fpn
2. add nasfpn_cell_factory.py

* reformatted

* fixed

* fixed

* Update nasfpn_cell_factory.py

* pre-commit

* bug fixed

* renamed&moved

* not done

* fixed

* fixed

* Delete remove_parawise_cfg_nasfcos_r50_nashead_4x4_coco.py

* fixed

* Create 1x_bias_lr.py

* Revert "Create 1x_bias_lr.py"

This reverts commit 54602ded283a8f646aebfa0f216350fd2ce82e6d.

* fixed

* fixed

* fixed docstring

* init modified

* formatted

* fixed

* updated

* fixed

* fixed

* fixed

* fixed

* fixed

* fixed

* pass test

* fixed

* fixed

* fixed

* rename

* 123

* nasfcos_readme

* Update README.md

* rename & leave empty

* GN->GN-head in README

* fixed

* Add upsample_cfg support in FPN

* small fix

* Add multiple extra conv sources

* small logical fix

* Add neck tests for fpn

* Add neck tests for fpn

* fixed several typos

* resolved issues

* Removed extra_convs_source option

* added necks to apis.rst

* change according to comments

* reconfigured configs