add fast rcnn api & fix minor bugs

mmdet/models/detectors/__init__.py

 from .base import BaseDetector
 from .rpn import RPN
+from .faster_rcnn import FastRCNN
 from .faster_rcnn import FasterRCNN
 from .mask_rcnn import MaskRCNN
 
-__all__ = ['BaseDetector', 'RPN', 'FasterRCNN', 'MaskRCNN']
+__all__ = ['BaseDetector', 'RPN', 'FastRCNN', 'FasterRCNN', 'MaskRCNN']

mmdet/models/detectors/fast_rcnn.py

+from .two_stage import TwoStageDetector
+
+
+class FastRCNN(TwoStageDetector):
+
+    def __init__(self,
+                 backbone,
+                 neck,
+                 bbox_roi_extractor,
+                 bbox_head,
+                 train_cfg,
+                 test_cfg,
+                 mask_roi_extractor=None,
+                 mask_head=None,
+                 pretrained=None):
+        super(FastRCNN, self).__init__(
+                    backbone=backbone,
+                    neck=neck,
+                    bbox_roi_extractor=bbox_roi_extractor,
+                    bbox_head=bbox_head,
+                    train_cfg=train_cfg,
+                    test_cfg=test_cfg,
+                    mask_roi_extractor=mask_roi_extractor,
+                    mask_head=mask_head,
+                    pretrained=pretrained)

mmdet/models/detectors/two_stage.py

@@ -146,7 +146,8 @@ class TwoStageDetector(BaseDetector, RPNTestMixin, BBoxTestMixin,
         x = self.extract_feat(img)
 
         proposal_list = self.simple_test_rpn(
-            x, img_meta, self.test_cfg.rpn) if proposals is None else proposals
+            x, img_meta,
+            self.test_cfg.rpn) if proposals is None else proposals[0]
 
         det_bboxes, det_labels = self.simple_test_bboxes(
             x, img_meta, proposal_list, self.test_cfg.rcnn, rescale=rescale)