Fix the order of import statements in __init__.py (#1094)

* fix the imports in __init__.py

* update contribution guide

mmdet/models/necks/__init__.py

-from .fpn import FPN
 from .bfp import BFP
+from .fpn import FPN
 from .hrfpn import HRFPN
 
 __all__ = ['FPN', 'BFP', 'HRFPN']

mmdet/models/plugins/__init__.py

-from .non_local import NonLocal2D
 from .generalized_attention import GeneralizedAttention
+from .non_local import NonLocal2D
 
 __all__ = ['NonLocal2D', 'GeneralizedAttention']

mmdet/models/utils/__init__.py

-from .conv_ws import conv_ws_2d, ConvWS2d
-from .conv_module import build_conv_layer, ConvModule
+from .conv_module import ConvModule, build_conv_layer
+from .conv_ws import ConvWS2d, conv_ws_2d
 from .norm import build_norm_layer
 from .scale import Scale
-from .weight_init import (xavier_init, normal_init, uniform_init, kaiming_init,
-                          bias_init_with_prob)
+from .weight_init import (bias_init_with_prob, kaiming_init, normal_init,
+                          uniform_init, xavier_init)
 
 __all__ = [
     'conv_ws_2d', 'ConvWS2d', 'build_conv_layer', 'ConvModule',

mmdet/ops/__init__.py

-from .dcn import (DeformConv, DeformConvPack, ModulatedDeformConv,
-                  ModulatedDeformConvPack, DeformRoIPooling,
-                  DeformRoIPoolingPack, ModulatedDeformRoIPoolingPack,
-                  deform_conv, modulated_deform_conv, deform_roi_pooling)
 from .context_block import ContextBlock
+from .dcn import (DeformConv, DeformConvPack, DeformRoIPooling,
+                  DeformRoIPoolingPack, ModulatedDeformConv,
+                  ModulatedDeformConvPack, ModulatedDeformRoIPoolingPack,
+                  deform_conv, deform_roi_pooling, modulated_deform_conv)
+from .masked_conv import MaskedConv2d
 from .nms import nms, soft_nms
 from .roi_align import RoIAlign, roi_align
 from .roi_pool import RoIPool, roi_pool
 from .sigmoid_focal_loss import SigmoidFocalLoss, sigmoid_focal_loss
-from .masked_conv import MaskedConv2d
 
 __all__ = [
     'nms', 'soft_nms', 'RoIAlign', 'roi_align', 'RoIPool', 'roi_pool',

mmdet/ops/dcn/__init__.py

-from .deform_conv import (deform_conv, modulated_deform_conv, DeformConv,
-                          DeformConvPack, ModulatedDeformConv,
-                          ModulatedDeformConvPack)
-from .deform_pool import (deform_roi_pooling, DeformRoIPooling,
-                          DeformRoIPoolingPack, ModulatedDeformRoIPoolingPack)
+from .deform_conv import (DeformConv, DeformConvPack, ModulatedDeformConv,
+                          ModulatedDeformConvPack, deform_conv,
+                          modulated_deform_conv)
+from .deform_pool import (DeformRoIPooling, DeformRoIPoolingPack,
+                          ModulatedDeformRoIPoolingPack, deform_roi_pooling)
 
 __all__ = [
     'DeformConv', 'DeformConvPack', 'ModulatedDeformConv',

mmdet/ops/masked_conv/__init__.py

-from .masked_conv import masked_conv2d, MaskedConv2d
+from .masked_conv import MaskedConv2d, masked_conv2d
 
 __all__ = ['masked_conv2d', 'MaskedConv2d']

mmdet/ops/roi_align/__init__.py

-from .roi_align import roi_align, RoIAlign
+from .roi_align import RoIAlign, roi_align
 
 __all__ = ['roi_align', 'RoIAlign']

mmdet/ops/roi_pool/__init__.py

-from .roi_pool import roi_pool, RoIPool
+from .roi_pool import RoIPool, roi_pool
 
 __all__ = ['roi_pool', 'RoIPool']