1. Change DataFormat from enum to enum class.

1. Auto transformation between data format, data type and memory type.
2. Add device placement optimization strategy.

1. Support int32 input data type.
2. Support GatherV2 op
3. Add transpose to ExpandDim op.

1. input_data_formats flag in yaml supports OIHW
2. MaceTensor support OIHW data format

1. Remove data_format flag for ambiguous
2. add has_data_format for distinguish models without data format.

1. Convert OpenCL binary files to code.
2. example support OpenCL byte stream with --cl_binary_to_code flag.

This reverts merge request !931

1. Add GPURuntime for GPUDevice
2. Move OpenCLRuntime to GPURuntime
3. Move ScratchImageManager from OPENCLRuntime to GPURuntime

1. Support memory optimization at runtime
2. Support memory type transformation automatically at runtime.
3. Move gpu winograd convolution to Conv2D.
4. Support Data Type transformation automatically.
5. MaceTensor API support optional data type.
6. Add input_data_formats and output_data_formats at yaml
7. Related issue(#363)

1. Move all files in kernels to ops
2. unify the op_def_registry and op_registry.
3. Support op clip: do not link the ops' code when the op is not registered.

1. Merge the Operation and OpKernel into Operation.
2. Add OpDefRegistry for registering the definitions of Operations.
3. Add information for MaceStatus.
4. Unify 'BatchNorm' and 'FoldedBatchNorm' into 'BatchNorm'
5. Remove unused op 'Proposal'