onnxruntime

Support seq(tensor), implement 2 sequence ops that use the new type. (#1983)

* Mention OrtCreateSessionFromArray in C API doc

* fix seq of tensors

* changes on 9/30

* All tests passing

* Add SequenceAt op

* Fix shared_lib non_tensor_types test

* Address some PR comments

* Address PR comments

* Add support in python bindings to accept seq(tensor)

* Change data type from vector<Tensor> to TensorSeq

* Change data type from vector<Tensor> to TensorSeq

* Added some documentation

* Added missing test model

* Fix Linux build

* Fix Mac build

* Fix Mac build