Update tracing module

[gmalivenko]

Due to new PyTorch updates the only way to proper handle weights and layer names at the same time - to use ONNX export.

From the next version of the converter, tracing module will be replaced. Hopefully it will open new features - converting modules such as ModuleList, converting recurrent networks and so on. Stay tuned.

The new tracing module will be placed to the separated repository https://github.com/nerox8664/onnx2keras and used as a library after implementation.

Progress:

• Model loading / parsing
• Convert convolution layers:
  • Conv2d
  • ConvTranspose2d
• Convert linear layers:
  • Linear (Gemm / MatMul)
• Convert pooling layers:
  • MaxPool
  • AveragePool
  • GlobalAveragePool
• Convert padding layers:
  • Pad*
• Convert normalization layers:
  • BatchNorm2d
  • InstanceNorm2d
• Activations:
  • ReLU
  • LeakyReLU
  • Sigmoid
  • Tanh
  • Selu
• Reshape operations:
  • View / Flatten *
  • Transpose *
  • Unsqueeze *
  • Shape *
• Also element-wise operations:
  • Div
  • Add
  • Mul
  • Sub
• Other operations:
  • Gather *
  • Clip
  • Exp
  • Log
• Implement new tests to cover converter
• Test new available models on torchvision