Add namespace to all files header + implementation

[david-alvarez-rosa]

All files have been 'namespaced'.

Testing

Build succeeds and executable run as expected.

[waifod]

Resolving my previous comments since they were addressed in the PR dealing with the formatting.

[david-alvarez-rosa]

Thank you for the detailed review! I didn't notice those.

And good to know that clang-format takes care of those automagically.