Provide a mechanism for running a code formatter on the generated bindings

As the final stage of generation, support running an automatic formatter (clang-format, gofmt, autopep8, etc.) on the template output.

This is preferable to making the templates themselves unreadable in an effort to produce readable generated code.

This is a really important item. Legibility of templates is really critical.

We could add a script to render templates legible or compact too. I'm not sure how aggressive we can convince clang-format to be at deleting blank lines.

Do we need to do this now that @ajbennieston's awesome work has made templates readable?