* collect env info for trouble shoting

* minor fix

* update the issue template

* fix the travis building

* update setup classifiers

* fix the imports in __init__.py

* update contribution guide

* restructure the ops directory

* add some repr strings

* add pytorch 1.1.0 SyncBN support

* change BatchNorm2d to _BatchNorm and call freeze after train

* add freeze back to init function

* fixed indentation typo in adding freeze

* convert SyncBN to BN when eval is called

* add gcb and configs

* fixed line too long

* fixed space and newline

* ignore too long line in config files

* two space before inline comment

* refactor var name

* fixed line too long

* changed SyncBN to backbone only and add non-Sync BN configs

* reformat config to adapt master branch

* reformat change method->type

* remoe some configs

* clean up readme.md

* add benchmark

* fix typo in README

* change sbn to syncbn

* change work dir

* refactor gcb

* fixed line too long

* Code formatting

* add two stage w/o neck and w/ upperneck

* add rpn r50 c4

* update c4 configs

* fix

* config update

* update config

* minor update

* mask rcnn support c4 train and test

* lr fix

* cascade support upper_neck

* add cascade c4 config

* update config

* update

* update res_layer to new interface

* refactoring

* c4 configs update

* refactoring

* update rpn_c4 config

* rename upper_neck as shared_head

* update

* update configs

* update

* update c4 configs

* update according to commits

* update

* add ga rpn

* test bug fix

* test bug fix with loc_filter_thr is large

* update configs

* update configs

* add ga_retinanet

* ga test bug fix

* update configs

* update

* init masked conv

* update

* update masked conv

* update

* support no ga_sampler

* update

* update

* test with masked_conv

* update comment

* fix flake errors

* fix flake 8 errors

* refactor bounded iou loss

* refactor ga_retina_head

* update configs

* refactor masked conv

* fix flake8 error

* refactor guided_anchor_head and ga_rpn_head

* update configs

* use_sigmoid_cls -> cls_sigmoid_loss; use_focal_loss -> cls_focal_loss

* refactoring

* cls_sigmoid_loss -> use_sigmoid_cls

* fix flake8 error

* add some docs

* rename normalize to norm_cfg

* update configs

* add readme

* update ga_faster config

* update readme

* update readme

* rename configs as r50_caffe

* merge master

* refactor guided anchor target

* update readme

* update approx mas iou assigner

* refactor guided anchor target

* update docstring

* refactor ga heads

* fix flake8 error

* update readme

* update model url

* update comments

* refactor get anchors

* update docstring

* not use_loc_filter during training

* add R-101 results

* update to support build loss api

* fix flake8 error

* update readme with x-101 performances

* update readme

* add a link in project readme

* refactor code about ga shape inside flags

* update

* update

* add x101 config files

* add ga_rpn r101 config

* update some comments

* add comments

* add comments

* update comments

* fix flake8 error

* add cpp sigmoid focal loss

* modify interface

* format cpp code, support, fix pep8 error

* format cpp code as google style