[Py] Added clamp operator to Python API. Created new package for registration of fused ops in pyngraph.

* Make required numpy version explicit.

* Read setup requirements from requirements.txt

* Update documentation for utility test functions.

* Remove unnecesary code and update comment.

* Added elu operator to Python API.

* Added missing file.

* Specified elu function description.

* Expand docstring

* [Py] Added test with scalar for elu operator.

* Bugfix

*  [Py] Changed input type in elu test.

* Update test_ops_binary.py

* [Py] Syntax bugfix.

* [Py] Added elu operator to list in documentation.

* Use libc++ for macOS core python wheel

* numpy version

* [ONNX] Add eyelike operator

* Use shifted square identity in square identity

* Make new helper function to map onnx_types<->ngraph_types

* Add fp16 support to ngraph Python API

* Move helper common.hpp => common.cpp

* Add checker for attribute presence

* Style check

* Add definition of shifted word

* Change return value of attribute presence !(==) -> !=

* Rename is_attribute_present => has_attribute

* Clean-up headers in eyelike.cpp

* Organize headers in common.*pp

* Minor review fixes

* Style check

* Add test for EyeLike with negative k

* WIP more guides and tutorials for the docs

* Update Guides and structure

* Update Guides and structure

+ Test documentation build on Clear Linux OS;
+ Fix a few links and redirs.
+ Note rc-naming conventions in doc may be tag-generalized.

* documentation supports various rc-naming conventions

* Add instructions on building nGraph bridge from src

* Update ngtf bridge versions to 0.14.1 and TensorFlow's bazel dependency to 0.24.1

* Use consistent file naming on all BE indexes

* Fix comma

* Templatize versioning for releases starting 0.20 and add placeholders for changes by components

* Remove typo

* Minor formatting fixed

* Document how to find or display built version of nGraph

* Start a r0.21 for doc that also fixes broken link and typo

* Correct use of console command context for version check

* Minor fixes to doc-contributor-README

* Docs for version 0.21

* Ensure docs build without error

* Assign ownership project README and intro for new ngraph.ai site to Straw

* Note deprecated Tensor API in doc

* Update to generic versioning on core doc for importing via built wheels

* Resolve merge conflicts leftover from v20 version request changes

* remove typo and suggested use of prebuilt LLVM since newer OSes do not have them available

* Update to latest

* Update with review from PR and ngraph bridge team

* Update right section with review from PR and ngraph bridge team

* Ensure doc example folders have owners from the component

* Push edit of tensorflow_connect to v0.22 docs

* Update Python wheel building instructions to newer version

* Enable INTELGPU backend for python tests

* Skip the test_replace_slice on iGPU

RuntimeError: Unsupported op 'ReplaceSlice' in IntelGPU back end.

* Reformat a function to satisfy flake8

* Yet another code formatting correction

* Fix of the failing tests: test_unary_op_array & test_unary_op_scalar

* Parametrize the logical_not test with input_data

* Code formatting

* Whitespace removal because flake8

* remove tensor offset from tensor read/write calls because it was never used

* fix build errors

* fix build errors

* fix python test errors

* more python fixes

* revert change

* Make old version of read/write deprecated

* fix python read overload

* one more try to fix python binding

* fix python

* yet another try

* why is this so hard

* fix?

* add text to changes.md

* wip

* build works with serialize disabled

* one more try

* disable unit test when json disabled

* handle case where serialize is disabled in python test

* one more fix

* Add create_dynamic_tensor function to Backend signature

* Add skeleton of dynamic wrapper class

* Simple test for construction

* Some progress on dynamic tensor creation

* Compile dynamic wrapper into core; change config string to a factory option

* Add wrapped executable, working on simple example

* Add wrapped dynamic tensor

* Update to match new tensor API

* Update wrapper to clone the graph; basic dyn test now passes

* Update call_with_validate to grok dynamic

* Make the unit tests a little prettier

* Make get_element_type virtual

* Change dynamic tests to be backend-parametric; fix get_element_type check for dyn tensors

* Add dynamic.in.cpp

* CODEOWNERS entry for dynamic_wrapper

* Remove overly-accommodating behavior for create_dynamic_tensor on non-dynamic BEs

* Pass enable_performance_collection to wrapped compile() calls

* More comments in the 'abc' test

* Fix 'create' wrapper in pybind11

* Remove unnecessary WrappedStaticTensor class

* Better names for the classes, and add some docstrings

* Fix pybind for 'create' to return shared_ptr now

* Interpreter working

* cleanup

* cleanup

* add CPU backend

* Update the rest of the backends

* update python API

* update test_case to use new shared_ptr

* Remove parameter, result, and node vector files and class, use vector

* Fix gcc issues

* style

* Remove python references

* update python files

* fix error

* fix build error

* Don't create a separate .so for python onnx importer.

* Pass outer make's -j values to sub make used in python_wheel.

* include rc version in NGRAPH_VERSION_SHORT

* Create a separate version string for python wheel.

* [ONNX] Erf op support

* [ONNX] Missing CMakeLists entry for the Erf op

* [ONNX] model_erf unit test excluded from GPU

* Update quoting style to fix errors raised by updated version of flake8.

* Change OneHot to accept only non-real types

* Update docstring

* Update Python test

* Add is_integral to element::Type

* Update docs

* Change is_integral to false for boolean

* Revert "Change is_integral to false for boolean"

This reverts commit 099ff378ae7fcbd1d9346665812f6b95e4886186.

* Revert "Add is_integral to element::Type"

This reverts commit 58fdf76fecaefdad10431f9a894523f326f3adca.

* Change is_integral so it is, by definition, !is_real

Update template for release notes and CHANGELOG with latest few summaries from ngraph releases repo (#2696)

* Update Release Notes for Github summaries, incorporate feedback from doc review, fix typos, etc

* Fix links

* Rename RCs on template

* PR reviews

* Remove trailing spaces and add clarification on Python API example

* Fix typo