* Add GPUKernelArgs for storing kernel arguments.

* Formatting.

* Resolve tensor addresses when extracting arg list via GPUKernelArgs.

* Updated arg list resolution so that placeholder arguments can be added anywhere in the argument list.

* const ref. args and changed add_args to use add_arg. also expanded type_names map.

* GPUKernelArgs bug fix for return values.

* add_placeholders expects pointers for later resolution

* Formatting.

* Add comments to GPUKernelArgs

* Changed GPUKernelArgs interface to use a runtime variable number of arguments.

* Removed/updated comment.

* Address review comments: Remove combined address resolution and argument list retrieval. Remove unecessary extra type entries in type_map.

* Add space between pragma once and includes.

* Broadcast optimization (#1322)

* Implement GPUKernelArgs with op::Broadcast.

* Removed excess type insertion in kernel signature for broadcast impl.

* Support new auto kernel signature generation for op::Broadcast. Add boolean to helpers to determine if parameters are registers or arrays.

* Removed commented code.

* Update broadcast impl. for new GPUKernelArgs interface.

* Updated based on interface change to GPUKernelArgs.

* Formatting.

* CUDNNHostParameters now implement GPUHostParameters. (#1324)

* Formatting.