Idea: in AutoGemm, use Jinja2 templates, rather than print statements

[hughperkins]

Idea: for AutoGemm, use Jinja2 templates, rather than print statements

You can look at the following files to see how it works:

• jinja2 template: https://github.com/hughperkins/pytorch/blob/master/src/PyTorch.jinja2.pxd
  • generated file: https://github.com/hughperkins/pytorch/blob/master/src/PyTorch.pxd
• jinja2 template: https://github.com/hughperkins/pytorch/blob/master/src/nnWrapper.jinja2.cpp
  • generated file: https://github.com/hughperkins/pytorch/blob/master/src/nnWrapper.cpp