[Feature]: Allow daylight levels to be configurable.

[kwvanderlinde]

Feature Request

Map daylight (present when vision is set to Day or Off) is currently set to a lumens value of 1. This was done in #3346 to ensure that even weak darknesses could still function, especially considering users upgrading existing campaigns. But having such a low lumens value does not align with certain mechanical expectations about day light. E.g., in my D&D 5e games, I expect day light to count as bright light. In fact, it should be among the strongest lights, not the weakest possible light, and so I expect weak darkness to be overcome by day light.

The Solution you'd like

I would like the existing map's Vision settings (called Lights in the Map Properties dialog) to be split up in the following way:

1. Vision would become a toggle: on or off. This toggle would only control whether the FoW visibility tests are done and would have no bearing on the map lighting.
2. A new per-map option is introduced to control the lumens level of general map lighting. This can be any non-negative integer and would control the level of what has previously been called "daylight". Existing uses of Day would be equivalent to setting this to 1, and existing uses of Night would be equivalent to setting it to 0.
3. When upgrading an existing campaign, the following cases are used:
   • If vision is set to Off, set the new vision toggle to off, and put the new lumens level at 1.
   • If vision is set to Day, set the new vision toggle to on, and put the new lumens level at 1.
   • If vision is set to Night, set the new vision toggle to on, and put the new lumens level at 0.
4. In the Preferences dialog, Interactions tab, do a similar replacement of the New Map Light option to instead be one checkbox for the default vision toggle and another for the default lumens levels for new maps.

Alternatives that you've considered.

Instead of having a per-map lumens slider, being able to mark different parts of the map as having different ambient lumens levels. E.g., a map might generally be run as daylight, but there's also a dark building that makes sense to treat as a night-like region. But I think any such option could be layered atop a general map setting, or could be solved in a completely different way.

Additional Context

This FR is partly inspired by a potential oddity with the lumens overlay FR (see some discussion in #3817 about that). But it's also motivated by the fact that daylight just doesn't align with expectations in my own game.

At the same time, I'm hoping to close holes in the existing configurations and simplify its understanding, even if it means adding an extra knob to turn. One hole is that there is currently no way to turn of the soft FoW visibility test while also have a night-time scene that requires lights and hard FoW reveals. And one part of the understanding aspect is that Day and Night are opaque options that - from a user's perspective - could change all sorts of of things. But a map-level illumination slider does what it says, and wouldn't be expected to do anything else.