* Remove unnecessary dependency on codegen in interpreter

* Check for incorrect return type and undeclared parameters in Function's constructor

* Address review comments

* Add scarier error message when the result node has null return type (should never happen)
* Add new constructor for Function that doesn't require the return type, and unit test for same

* New Interpreter backend

* PR review comments

* More RP fixes

* oops

* make autodiff tests backend aware

* wip

* wip

* more ops

* wip

* fix merge error

* merge fixes

* We were pushing parameters that have been seen to the stack in traverse nodes. This causes an infinite loop in RNNs.

* fix formatting

* style fix for Scott

* Simpler kernel for broadcast

* Fixed behavior for integer divide-by-zero, added unit tests

* Strided and higher-dimensional slice (just tested to 3D)

* Higher-dimensional sum

* Replace-slice de-Eigenized; NOT TESTED AT HIGHER DIMENSIONS YET

* Correct sum behavior when eliminating zero-length axes; add unit tests; also, add higher-dim unit tests for replace-slice

* Higher-dimensional reduce, 'cause hey, why not?

* Remove BroadcastScalarInstruction

* Adding test for an observed failure at trivial sum on 5-tensors

* De-Eigenized and higher-dimmified concat

* Replace 'auto' in the kernels

* temporary delete to ease merge

* Re-insert tests that were deleted to ease merge

* Refactor view-iteration

* De-Eigenize reshape

* Rework divide kernel to use std::enable_if to distinguish between floating and non-floating types

* Update docs to reflect newly implemented cases in several ops

* Rename parameters to View for more clarity; remove axis_walk_order (it's redundant)

* Formatting

* More terminological rejiggering

* De-Eigenize scalar-tensor product

* De-Eigenize dot

* Update docstrings

* Remove 'implementation status' tables from docstrings

* Change step -> strides everywhere for consistent terminology

* Formatting

* Replace asserts in view.cpp with exceptions

* Fix typo

* Fix incorrect result type in dot1d test (ouch...)

* Add missing support for Float64 to ngvm/external_function

* Add int16 and uint16 (how was this missing?)

* A few more additions relative to the missing element types

* Disable tests that will not pass on CPU; they can still be run with test/unit-test --gtest_also_run_disabled_tests --gtest_filter='DISABLED_NGVM.*'

* Move project_ and inject_ functions to common.[ch]pp, not view.[ch]pp

* Rename View to CoordinateTransform

* Add prefix ++ and += to CoordinateIterator

Work so far on de-Eigenization

* move replace_node to util

* static run_matchers_on_nodes_list

* switching to map

* formatting

* addressing Scott's feedback and fixing warnings

* more pattern matcher refactoring

refactoring cont'd

* Add numpy_transpose to the builder for numpy-stype transpose operations

* fix docstring

* make sure to throw the error

Merge branch 'aprocter/de-eigenize' of github.com:NervanaSystems/private-ngraph-cpp into aprocter/de-eigenize

* add json lib 2.1.1

* add json serialization of graph

* cleanup

* enhance unit test

* remove FunctionProvider class and replace with virtual get_function() in Node

* remove json code from element_type

* move serialize to be directly in the ngraph namespace. cleanup header file.

* add cname check to element::operator==

* add using json = nlohmann::json