option should not be overridden by subsequent options of the same module.

* fix gpu detection issue on windows
1. use the fluid.core.get_cuda_device_count() to decide the GPU number
2. ignore the path missing issue

* add log iter argument

* ppdet log time smooth

* ppdet log eta

* refine gan

* fix infer doc and config default

* refine dataset exists

* fix None proc

* add rpn recall function and class-aware rpn

* fix dir and gpu

* fix yolov3 subprocess not exit

* refine print

* fix2744

* remove useless comment

* make code less ugly

* optimize error message when result is none

* fix save_inference_model cannot find feed vars

* remove comment

* fix format

* add comment for pruned var

* add log for prune

* fix resnet for resnet34

* fix ResNet18 and ResNet34

* update modelzoo and fix configs

* fix configs

* fix resnet bn

* update readme

* rm useless png

* fix bn warning

* Clean up a bit

* Add `__shared__` annotation for shared variables between modules

* Dedup `num_classes` configurations

* Document `__shared__` usage

* Remove some unused variable

* Improve docstring and add comments for `__shared__`