Menu and UI update part 2

I kept working on the menus this month. I added a "settings" part in the pause menu with new options.

• Added settings for music volume and sound volume in there

• Added settings for fullscreen and windowed in there

Other options in that settings screen (control mapping & language) aren't implemented yet, although you can still configure your controls from the main menu.

• Control mapping menu can now be navigated with keyboard

• Added a "reset controls to default" button in there, as well as a "confirm controls" button which prevents errors

• Implemented menu icons lighting up properly and added some help text to navigate menus (there's still a few errors lurking that I must fix)

• The new settings are saved when you update them

And that's it for this update. There's still menu stuff to do but my priorities lie elsewhere right now, I will be focusing on making the demo feel polished for the steam next fest to come.