* allow forwarding for multi scale inputs

* fixed PadBatch not working with multi scale input

* add faster_rcnn_r34_fpn_multiscaletest_1x_coco.yml

* fixed multi scale input checking for batch transforms (PadBatch)

* less scales and faster inference for multi scale test configuration file

* fixed retrieving im_id from multi-scale inputs

* add multi scale prediction boxes merging

* allow multi scale testing for tools/infer.py (actually trainer.predict method)

* add MultiscaleTestResize setting for TestReader

* use BBoxPostProcess.nms parameter for multi scale prediction NMS of CascadeRCNN

* add documentation for multi scale testing

* raise exception if the network architecture is not supported in multi scale test mode

* move documentation file

* add test case for multi scale test

* load pretrained weights from URL

* add image files for testing. use relative path for input images

* update documentation

* use isinstance for sequence type checking. add empty checking for samples sequence

Besides removing unnecessary imports, this also fixes the missing logger module in test_architectures.py within the static directory.

* add model_zoo unittest

* update 2.0.1

* update solov2 some detail

* fix check paddle version

* add enable_static()

* follow comments

* remove blank line

* update version require for ppyolo

* optimize python path

* Polish Reader to simplify preprocessing logic.
#  sample_transforms-> make batch -> batch_transforms in Reader.
* Clean some code
* Imporve yolov3_r50vd_dcn_obj365_pretrained_coco 41.4 to 41.8.
* Update all configs.

* Rename object_detection to PaddleDetection
* Small fix for doc