Add .clang-format

[valgur]

Hi!

I recently ported (N)compress over to C++/Python since Python was lacking a good implementation of LZW compression + decompression. I hope you don't mind me using the "ncompress" title as the package name.

One of the by-products of that was a .clang-format rules file to make development easier but still keep the formatting consistent with the source. I did my best to match the rules to the existing formatting and I think it manages that quite well, with the obvious exception of all function bodies no longer being double-indented.

So, here's a PR with the autoformatting and some minor formatting tweaks applied. I hope you find this useful. If you would rather keep things as is, though, (e.g. to keep 'git blame' cleaner) then that's absolutely okay by me, too.