* [DOC] CoreML frontend tutorial

* Update tutorials/frontend/from_coreml.py

Co-Authored-By: kazum <morita.kazutaka@lab.ntt.co.jp>

* Update tutorials/frontend/from_coreml.py

Co-Authored-By: kazum <morita.kazutaka@lab.ntt.co.jp>

* Addressed comments and added the original author

* [Tutorial][Frontend] move from_keras tutorial to frontend

* remove tutorial/nnvm/from_keras.py

* [RELAY][FRONTEND] Tensorflow frontend support.

* 	* LSTM removed for a while.

* 	* basic ops are good.

* 	* nn wip

* 	* wip

* 	* python2.7 corrections.

* * NN ops are good.

* * e2e models working good

* 	* all good except LSTM

* 	* rebase, tutorials and CI trigger.

* 	* CI errors.

* 	* enable opt_level=3

* 	* Docstrings cleanup. testing.tf utils moved to relay from nnvm.

* 	* tutorials update.

* 	* LSTM work good now.

* 	* Rebase

* 	* CI error

* 	* enable PTB.

* 	* rebase.

* 	* tutorials

* Update python/tvm/relay/frontend/tensorflow.py

Co-Authored-By: srkreddy1238 <sivar.b@huawei.com>

* 	* review comments.

* 	CI fix.

* 	* review comments.

* [Relay][Frontend] Add Caffe2 Support

* [Relay][Frontend] Add Caffe2 Support (fix unsed import)

* [Relay][Frontend] Add Caffe2 Support (fix caffe2 model import)

* [Relay][Frontend] Add Caffe2 Support (fix model install and reflect code reviews)

* [Relay][Frontend] Add Caffe2 Support (fix caffe2 model import)

* [Relay][Frontend] Add Caffe2 Support (fix caffe2 model import)

* [Relay][Frontend] Add Caffe2 Support (fix caffe2 model import)

* [Relay][Frontend] Add Caffe2 Support (fix caffe2 frontend import)

* [Relay][Frontend] Add Caffe2 Support (rename function name in test_forward)

* [Relay][Frontend] Add Caffe2 Support (fix caffe2 model import)

* [Relay][Frontend] Add Caffe2 Support (fix caffe2 model import)

* [Doc] Caffe2 frontend tutorial

* [Doc] Caffe2 frontend tutorial

* [Doc] Caffe2 frontend tutorial

* [Relay][Frontend] Add Caffe2 Support (remove unsed file)

[TFLite][Python 2] Solve TFLite frontend python 2 compatibility and Modify TFLite whl files path (#2529)

* TFLite frontend tutorial

* Modify as suggestion