Add Warm lighting

[IonicCheese]

Goal of this PR is to enhance Luanti's shaders with Warm artificial lighting

This PR adds warm lighting to Luanti as a simple but great way to enhance Luanti's visuals

When enabled will make light sources emit warmer lighting giving a more realistic/cozy (this effect is not very noticeable if the area you put the light has a lot of sunlight)

Before/After images:

Ready for Review

How to test

1. go to settings -> Effects -> Enable "Warm Lighting"
   (optional but recommended is to enable "Filmic Tone mapping" under "Post Processing")
2. place some light sources in the dark

[sfan5]

This needs to be configurable using a server API, not the client.
Also "warm lighting: yes/no" is not flexible. What if a modders want the lighting to be much colder or much warmer?

[cx384]

See here for colored lighting: #2670

Imo, the feature of this PR is too arbitrary and inflexible. Also, it could make things more complicated if we will eventually add a colored lighting API for artificial lights.

[alwayshopeless]

Please, no.
Adding more hardcode is a very bad idea, especially in the lighting system.

It would make much more sense to make artificialLight modifiable, but that would also affect all existing light sources and could potentially hinder the global illumination implementation (the difference between the adjustable color of global illumination and artificial light could be too big)

Therefore, I wouldn't recommend touching this at all until global illumination is added to Luanti

[IonicCheese]

im working on making it configurable by the client using another setting. (i can make it configurable by the server as well)

Please, no. Adding more hardcode is a very bad idea, especially in the lighting system.

It would make much more sense to make artificialLight modifiable, but that would also affect all existing light sources and could potentially hinder the global illumination implementation (the difference between the adjustable color of global illumination and artificial light could be too big)

Therefore, I wouldn't recommend touching this at all until global illumination is added to Luanti

Clarify "global illumination".

[sfan5]

im working on making it configurable by the client using another setting. (i can make it configurable by the server as well)

In case that wasn't clear, this must be server-controllable and may be client-controllable (as long as the server has the last word).

[veprogames]

#15417 proposes an option to set the artificial light color freely

[DragonWrangler1]

because of the fact that #15417 is older, perhaps it'd be best to go through with that one.