* add ppyolov2

* fix bugs and modify docs

* modify code and doc according to review

* fix bugs while resolving conflicts

* add 2.0 CHANGLOG

* update README

* update doc, test=document_fix

* add citation

* update citation and ppyolo doc

* add PP-YOLO tiny

* add pssdet model

* fix name of pretrain weights

* format, test=document_fix

* add senet

* add annotations according to review

* Add S2ANet model for Oriented Object Detection.

* update slim model

* fix skip quant

* add docs for custom dataset, reader and model technical

* modify docs according to review, test=document_fix

* modify READER.md, test=document_fix

* fix warning

* add static notice

* refine ppdet file name

* unify bbox_utils

* add Distill model
* add distill+prune

* fix path of script, test=document_fix

* update for ci-travis, test=document_fix

* update files

* update for ci-travis

* add benchmark, test=document_fix

* update style of number, test=document_fix

* add difference of dynamic shape and fix shape

* add config annotation doc, test=document_fix

* update doc of config

* mlp_dim-->out_channel of TwoFCHead

* add fcos ttfnet coment, update modelzoo

* fix ttfnet coment

* fix paddle inference name problem, and update doc

* set default value

* fix inference lib name in static

* update deploy doc, fix build error of windows

* add annotation of PADDLE_LIB_NAME

* set min_subgraph_size=33 as default, fix bug of fcos_dcn_r50_fpn_1x

fis the issue in function _get_shared_memory_size_in_M in the case of that there are multiple 'shm' space (#2434)