GSoD week 8

 Hi!

I'm posting a bit later than planned but I wanted to make sure one of the crucial PRs goes in before.

I've made some good progress this week and I am hugely thankful to @criezy for quickly jumping onto my reviews and leaving tons of great comments, some of which allowed me to understand the code better.

The biggest achievement of the week is that PR#2612 went in with some serious doxygen improvements in two big files: stream.h and system.h. Well over 2,5k lines of code overall. One significant change I made in system.h was the introduction of doxygen groups into the file (discussed in discord), so that now the documentation has a nice structure that is also reflected in the navigation pane on the left. I'm hoping this will improve the usability by a lot. Previously everything was presented on one page and because this is the largest header file in the scummvm codebase (or at least I believe so), this made the doc look a bit messy.

PR#2535 went in as well after a series of reviews.

Right now, I am preparing to open a PR for the last five high-priority files in the common folder (almost done locally). Then, I am moving on to engines, graphics, image, and audio. In each of these folders, we have identified a few header files as high priority.

For once I am happy with my progress this week and I'm truly hoping that in the next post I will be able to report that I am moving on to medium-priority files. Some of these have actually already been reviewed before we came out with the whole prioritization idea.