* Resolved problems with too restrictive data type

* Apply suggestions from code review

Code review remarks introduced
Co-Authored-By: Tomasz Socha <tomasz.socha@intel.com>

* Code review remarks. Part.2
Co-authored-by: Tomasz Socha <tomasz.socha@intel.com>
Co-authored-by: Adam Rogowiec <adam.osewski@intel.com>
Co-authored-by: Sang Ik Lee <sang.ik.lee@intel.com>

* Update license to new year

* Pick up some strays

* Implemented downgrade pass

* Using Pad:v1 in onnx_importer

* Downgrade transformation doc fixed

* Downgrade pass added for all backends

* Apply suggestions from code review

Changed pad_opset_pass to opset_downgrade
Co-Authored-By: Tomasz Socha <tomasz.socha@intel.com>

* Changed order of passes

* Changed downgrade pass order of CPU backend

* Code review remarks introduced

* Pad:v1 was introduced

* Fixed problem with foward declaration

* Code review remarks introduced

* Addtinal asserts and unit-test for Pad:v1 introduced

* Handled optinal arg_pad_value input

* Fixed unit tests messages and clang styles applied

* Styles applied, checking rank improved

* Updated changes.md

* Revert "Updated changes.md"

This reverts commit 8ee16e580705275ee0719648d5251021354e4d84.

* Clang warning fixed

* Start splitting type_prop.cpp (just a few for now, to get feedback on general pattern)

* Split out some more type_prop stuff

* A bunch more

* Move one test out of type_prop into build_graph

* Split Reverse from ReverseSequence (oops), and fix a typo I noticed in dyn_reshape.cpp

* fix EOF newline

* Style.

* Add newline at eof.