* add mask fpn r50 2x & minor fix for MODEL ZOO doc (#2747)

* cherry-pick bug fix for release/1.5

* fix mask eval for multi-batch (#2772)

* cherry-pick bug fix for release/1.5

* fix faster rcnn use im_shape (#2779)

* cherry-pick bug fix for release/1.5

* refine bbox_normalize in infer.py (#2781)

* refine bbox_normalize in infer.py

* add is_bbox_normalize

* rename _forward to build

* check callable

* cherry-pick bug fix for release/1.5

* Prevent module instance from modifying global config (#2790)

some of the global config values are reference type, e.g., objects, lists or
dicts, if the created module instances modify those values (see FPN and
spatial_scale), global config will reflect these changes, and instances of the
same class created later will inherit the changed values

* Fix command line parsing for non module options (#2839)

* fix save_inference_model cannot find feed vars (#2842)

* fix save_inference_model cannot find feed vars

* remove comment

* fix format

* add comment for pruned var

* add log for prune

* Fix train+eval in PaddleDetection(#2847)

* resolve conflict merge error

* reset data_feed