Add new setting to enable/disable dark mode in main menu

[sfan5]

adopted #16239
fixes #11308 (though no stars)

How to test

1. Go to Settings -> User Interface
2. Set "Menu theme" option to 'dark' (requires leaving settings menu to take effect)

[wsor4035]

how complicated would it be to have an auto default option that follows the systems preferences? - most software/websites do this. looks like sdl has a method for this: https://wiki.libsdl.org/SDL3/SDL_SystemTheme (but it is sdl3)

[sfan5]

Not hard, but won't implement since we don't use SDL3 by default anywhere at all.

[siliconsniffer]

It's a small but solid improvement, and I'm in favor of a feature like this.

Personally, I would prefer a night sky with stars, but I am unaware how technically feasible that is.
If there was some kind of daytime for the main menu background (like in-game), it could be synchronized with the local time, but that's just an idea.

[CrazyladMT]

Personally, I would prefer a night sky with stars, but I am unaware how technically feasible that is.

My friend and I have in fact implemented this, and they even twinkle too. We should open a PR soon...

[a-bad-dev]

Personally, I would prefer a night sky with stars, but I am unaware how technically feasible that is.

My friend and I have in fact implemented this, and they even twinkle too. We should open a PR soon...

IMO this looks much better with stars.

Our fork already has this, steal the code from here:

IonicCheese/erbium@00dbbf2
IonicCheese/erbium@dcfa7a7

(credit to @IonicCheese and @CrazyladMT for the stars)

[sfan5]

Our fork already has this, steal the code from here:

Drawing 2D rects without batching is not that efficient and IMO it would be better to extract and share the stars with the in-game sky code anyway.

Either way: I agree stars would be nice but let's get this incremental improvement merged first.

[IonicCheese]

Drawing 2D rects without batching is not that efficient and IMO it would be better to extract and share the stars with the in-game sky code anyway.

Im not good with Irrlicht/C++ lol, i did what worked ¯_(ツ)_/¯