Provide default code formatting with a .clang-format

[fire]

It'll be helpful to standardize on the author's coding style for consistency.

[fwsGonzo]

I've tried to use clang-format before, but the formatter (rather, the configuration) is not able to match my coding style. So I could not use it. I'm still interested in auto-formatting the code, but I will need something that is close enough to the real thing.