Add Colab Training Tutorial (#3213)

* Add colab training tutorial

* Update tutorial codes and fix bug

* Clean files, refactor TBD

* Update tutorials

* Remove duplicated code

* Mv tutorial

.isort.cfg

@@ -3,6 +3,6 @@ line_length = 79
 multi_line_output = 0
 known_standard_library = setuptools
 known_first_party = mmdet
-known_third_party = PIL,asynctest,cityscapesscripts,cv2,matplotlib,mmcv,numpy,onnx,pycocotools,pytest,robustness_eval,roi_align,roi_pool,seaborn,six,terminaltables,torch,torchvision
+known_third_party = PIL,asynctest,cityscapesscripts,cv2,matplotlib,numpy,onnx,pycocotools,pytest,robustness_eval,roi_align,roi_pool,seaborn,six,terminaltables,torch,torchvision
 no_lines_before = STDLIB,LOCALFOLDER
 default_section = THIRDPARTY

README.md

@@ -102,7 +102,7 @@ Some other methods are also supported in [projects using MMDetection](./docs/pro
 Please refer to [install.md](docs/install.md) for installation and dataset preparation.
 
 
-## Get Started
+## Getting Started
 
 Please see [getting_started.md](docs/getting_started.md) for the basic usage of MMDetection. There are also tutorials for [finetuning models](docs/tutorials/finetune.md), [adding new dataset](docs/tutorials/new_dataset.md), [designing data pipeline](docs/tutorials/data_pipeline.md), and [adding new modules](docs/tutorials/new_modules.md).
 

mmdet/models/detectors/base.py

-import warnings
 from abc import ABCMeta, abstractmethod
 from collections import OrderedDict
 
@@ -340,6 +339,4 @@ class BaseDetector(nn.Module, metaclass=ABCMeta):
             out_file=out_file)
 
         if not (show or out_file):
-            warnings.warn('show==False and out_file is not specified, only '
-                          'result image will be returned')
             return img