* finally have something almost acceptable

* Update cmake files to more modern approach

* disable building libraries that are not required

* handle more build cases

* add versions to backend libs. add start of package target.

* add create_backend to backends

* temporary workaround to tbb not linking correctly with gcc

* install codegen lib

* force tbb to link to the cpu backend so that it is available for codegen

* fix clang build error

* fix warning for codegen build

* update cuda header paths

* change error message for opening backend shared library

* set lib path

If user manully provide MKLDNN_INCLUDE_DIR and MKLDNN_LIB_DIR, don't
build mkl-dnn and just add a dummy external project "ext-_mkldnn" to
satisfy target dependency for the rest of the build.

* Enable NNP reverse build, clean up ngraph repo

* clean mkldnn cmake

* Add mechanism for disabling specific backend unit tests from a manifest file.
Populate the test manifest files for CPU, GPU and INTERPRETER.

* update docs for new manifest controlled transformer unit tests

* Minor changes for AllReduce

* migrate files

* apply version number to libngraph.so

* fix cmake running with empty build directory

* Remove usage of CMAKE_MAKE_PROGRAM as it slows down parallel build

* Make make properly propagate to child and add back targeted build.

* Revert "Make make properly propagate to child and add back targeted build."

This reverts commit b4b1d8db0f0d42850e53d4e0f773261c292ccaf6.

* Fix clang warnings on macos

* Conditionalize warning on Apple clang version.

Fix LLVM commit hashes to work around recent version bump incompatible with our hard-coded "5.0.1" paths (#781)

* update nnp transformer path

* topolotical-sort based node clustering

* cmake builds

* Argon manager renamed to NNP along with placement

* nnp dir cmake changes

* tests pass

* more renames

* somemore renames

* reslove redefination

* revert to ARGON_API

* more PR comments and remove nnp-fusion tests as redundant

* update path

* fix format

* CPU: Update Eigen

* CPU: Move patched Eigen master branch to NervanaSystems

* Add flags for SDL-3 compliance

* change check to support older versions of CMake

* patch working

* wip

* fix patcher

* remove debug message:

* cleanup

* fix typo

* Exit build with error message when NGRAPH_USE_PREBUILT_LLVM is requested on non-Linux OSes

* add support for both command line arg and env var to set NGRAPH_WARINGS_AS_ERRORS'

* make json lib an external project
* add env var to turn warnings to errors

* initial support for hybrid transformer

* add broadcast_vector_rowwise_reversed for hybrid test

* headerc

* get function placement fix

* conv ref test generator graph node in labmda fuction

* rename map_parameter_to_source_node

* type change map_parameter_to_source_node

* use interpreter for numerical derivative

* better comments

* Allow caching of external dependencies (everything but TBB, which I can't figure out yet)

* Tweaks to get CPU backend building and linking (but not actually working) on macOS

* Tweaks to codegen/CPU backend to enable macOS (no builtin headers yet)

* Re-enable header caching stuff on macOS

* Suppress unsupported compiler warning for Apple Clang

* Fix includes for macOS compatibility

* revert to shared argon lib

* installs argon headers

* -DINSTALLED_HEADERS_PATH=${CMAKE_INSTALL_PREFIX}/include

* formatg

* remove debug info

* revert

* revert back to cpp-master

(Squashing this commit but going to leave the full log here, unlike the way I usually do things)

* Incremental work on compatibility with system requirements

* Lower cmake version requirement so we can work with CentOS 7.4

* Disambiguate isnan call (CentOS's compiler doesn't like it)

* Make external_tbb conditional on NGRAPH_CPU_ENABLE

* Make MKLDNN inclusion conditional on NGRAPH_CPU_ENABLE

* Roll back desperation change to Ubuntu 14.04 binaries

* De-revert copyright date change (arrgh)

* Revert change of TBB's hard-coded compiler choice to gcc

* Cleanup of modified CMake stuff

* Add broken support for building LLVM from source

* Explain modification to json.hpp required compiler version

* Make TBB optional, and on by default. To disable, cmake -DNGRAPH_TBB_ENABLE=FALSE

* Add reasonable default for LLVM's CMAKE_ASM_COMPILER so users don't have to specify it

* Force TBB disabled if CMake is too old to build it (for CentOS)

* Build LLVM OpenMP as external project

* Tweak LLVM build options

* Minor comment edit in cmake scripts

* Workaround (fix?) for codegen crashes on CentOS

* Add some header paths for CentOS to resource_generator; temporary(?) tweak to ignore nonexistent paths

* Remove CMake compatibility figleaf since LLVM will require 3.1+ anyway

* Fix the TBB-enable flag to default to on

* Remove hard-coded choice of clang as tbb compiler

* ln -s -> ln -sf in command to create link for OpenMP source dir

* Make OpenMP build so it doesn't require symlink

* Allow use of prebuilt LLVM if requested at cmake time

* Some INSTALL instructions

* Allow NGRAPH_USE_PREBUILT_LLVM to be set in environment variable

* Tweak CI cmake options to use prebuilt LLVM

* Remove debug messages

* Rework defaulting behavior for LLVM_TARBALL_URL and LLVM_SHA1_HASH

* Remove warning message for unavailable header file directories

Update to newer version of MKLDNN with verbose debug output. Pull from github.com/intel/mkl-dnn instead of github.com/01org/mkl-dnn