Use code formatting tools

[AntoineRondelet]

There are a few inconsistencies in term of code style in the code base. I think it'd be great to remove these style-related discrepancies to keep a code base uniform (ideally, we should not be able to distinguish between the authors of 2 randomly selected files of the code base). Removing frictions related to code-style allows to focus fully on the "algorithmic part" (what really matters) for reviews.

Languages like Golang come with some tooling like GoFmt that runs on the code and formats it "the standard way". I quickly DuckDuckGoed "code formatter cpp" and it seems tools like this exist for cpp too. I haven't used any of them, but from my flash reading it seems that clang-format is a good candidate and is nicely configurable (see: http://clang.llvm.org/docs/ClangFormatStyleOptions.html). Maybe we can go for this one.

[EDIT:] I can see that we can base the clang-format config on some style-guides (like: https://google.github.io/styleguide/cppguide.html). This is exactly what I was looking for. Let's use such style guide here (I quite like Google's one actually) to avoid spending time defining ours and arguing about style issues.

[AntoineRondelet]

Maybe @dtebbs you know some other code formatters, or have a favorite one that we could use?

[AntoineRondelet]

Closing as the corresponding pull request has been merged