* [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