Module dependency tree generation is done!

This is a very simple and most certainly wrong preprocessor for C++. This was not done with any major intents, it was simply to test Rust and its capabilities (I find learning by doing a lot more useful than just following tutorials).

As a rust novice, I do not claim this to be of any quality.

So far, the most rellevant missing things are:

• the #line directive is not supported (and probably won't for some time, I do not intend to support generated code for now :) )
• QOL Features of preprocessors, like any pragma directive (none mandated by standard, but #pragma once is expected from any sensible implementation), or the __FUNCTION__ macro (which requires the step 7 parser to be implemented in order to know such information)
• Most test macros are kinda useless right now. __has_cpp_attribute is literally just hardcoded to 0

I'd say that the first 4 steps of the compilation process of C++ are done-ish! Time for lexing.

If you want more logs on what's going on, you can use the environment varaible RUST_LOG, like so: RUST_LOG=debug