* update mask_rcnn_fpn model

* update smooth_l1_loss

* update smooth_l1 and sigmoid_cross_entropy_with_logits

* fix relu name

* update reader in dygraph

* update dataloader some detail

* fix num_classes with background

* split config into models, optimizers, dataset, readers，runtime

* update YOLOv3 config

* add matrix nms api

* add test error in matrix nms ut

* modify code according to review

* modify matrix nms api

* add yolo_box and add unittest of yolo_box.

* update comment

* update sample code, call op in ppdet

* migrate roi_align and roi_pool to ops

* modify code according to review

* migrate detection ops from Paddle to PaddleDetection

* add unittest for detection ops

* update api & unittest

* add copyright & api name to migrate

* refactor dygraph & add mask rcnn fpn

* fix initialization & minor update

* refine architecture of mask_rcnn

add cascade rcnn and modify make net method
add new cfg method 
add auto debug tool

add yolov3

add faster rcnn\mask\cascade rcnn model arch\module\op
add base debug func in bufferdict 

clear directories & files for dygraph branch 

* add version check

* update version check & python version for cornerpool

Add `lr_multi_list` param for SSLD pretrained models' usage.

* activate scale_x_y

* update cspdarknet pretrained model

revert `reshape` changes

* optimize python path