Add dark presets to theme3 - #2207

This contains commits from #1805 because I started working on it before #1805 was merged.

@mxmou Should I wait until this is not a draft to review?

@WorldLanguages I still need to remove the changes I made to the auto refresh code in the userscript while working on this, but the rest is done.

All presets now define all colors, because the previous behavior was confusing.

@mxmou Do you think we should mark the addon as "new" for v1.14.0 so that people notice the presets? 🤔
Or do you have any better ideas on how to handle this for the feature
Maybe an "updated addons" group on the settings page, that lets us describe the update?

I think we should rename the "New" group to "New and updated"

I think we should rename the "New" group to "New and updated"

Yeah, not now, but maybe for next release

I think we should rename the "New" group to "New and updated"

Yeah, not now, but maybe for next release

but if we did it now, addons like cat blocks, ocular, and this one would fit into the category a bit more

@WorldLanguages If we don't do that now (I think a separate "updated" category is better), I think we should mark theme3 and ocular as new because they have important new features.

@mxmou

All presets now define all colors, because the previous behavior was confusing.

The presets don't need to change all the settings. This was an intentional feature of the presets. It allows you to change only groups of the needed settings, while not resetting other user values

@ZenithRogue I think all presets should affect the same group of settings. Previously choosing "2.0 Colors", then "3.0 Tweaks" would use the original 2.0 colors for everything except events, control, and custom blocks, which is likely not what any user wanted. The addition of these new presets made things even more confusing, because switching to "Dark", then "Black" (many people would probably do this when playing with the settings because the two presets were next to each other) made the text almost black on a black background.

I agree that the ability to leave certain settings unchanged when switching presets is sometimes useful - I don't want #2415 to be affected by presets - but I don't think it makes sense in this addon, especially because users can now use the reset button to only load certain colors from a preset.