More aggressive static declarations

[MaddTheSane]

Pull Request Type

• [ ] GitHub Workflow changes
• [ ] Documentation or Wiki changes
• [X] Build and Dependency changes
• [X] Runtime changes
  • [ ] Render changes
  • [ ] Audio changes
  • [ ] Input changes
  • [ ] Network changes
  • [X] Other changes

Description

This more aggressively marks functions and variables as static, as well as marking some values as constexpr. Also included are a lot of comments, mainly remarking if a function is only used in one source file, or if it is unused in Descent 3 (and thus could probably be removed).

Related Issues

~~This patch does incorporate changes from #346. These can be reverted.~~ A recent rebase removed the DallasFuncs changes.

Checklist

• [X] I have tested my changes locally and verified that they work as intended.
• [X] I have documented any new or modified functionality.
• [X] I have reviewed the changes to ensure they do not introduce any unnecessary complexity or duplicate code.
• [X] I understand that by submitting this pull request, I am agreeing to license my contributions under the project's license.

Additional Comments

Opened as a draft because this isn't complete, as well as wanting feedback about functions that aren't used by Descent 3 (either cut content incomplete features, or code that only used by the editor).