Add C++ code linting

[mcopik]

We should use clang-format and `clang-tidy.

[mattnappo]

Is there any preference on which clang formatting style to use? The available options by default are LLVM, GNU, Google, Chromium, Microsoft, Mozilla, WebKit

[mcopik]

@mattnappo Thanks for your interest in the issue! We already have a working LLVM-based Clang format in another project that we should use.

However, applying the format will likely require a lot of work across the project, and we plan on doing that right before wrapping up release v1.0 - so it might not be the best issue before a GSoC proposal. However, the format will definitely be there for GSoC :-)