Code guidelines

[Alex Henrie]

Hello everyone,

I just finished rewriting the Wine coding guidelines based on feedback
at https://gitlab.winehq.org/wine/wine/-/merge_requests/3059. Please
look it over and let me know if there's anything that I missed or
misstated:

https://wiki.winehq.org/Submitting_Patches#Code_guidelines

https://wiki.winehq.org/Wine_Developer%27s_Guide/Coding_Practice

Thanks to Zeb and Alexandre in particular for the clarifications about
style and compatibility.

-Alex