* Fix the "Enable debug logging" checkbox so that it properly disables "Enable verbose debug logging" when it gets disabled
* Avoid asking ImageWidget for alpha-blending when it's not useful
* Make ImageWidget's alpha-blending code-path double-check that alpha-blending actually is needed, and avoid it if possible
* In the same vein, only do alpha-blending in textboxwidget when absolutely necessary
* Prefer color constants over the gray() method, ensuring that they're part of the eInk palette
Depends on https://github.com/koreader/koreader-base/pull/853Fix#4774
* The Great 8bpp Experiment
Swap to 8bpp on Kobo, because we're 'effing grayscale, for pete's sake!
* Always swap to 8bpp, no matter the launch method.
Because it turned out that, even when restarting Nickel, we had to
restore the expected bitdepth ourselves, because pickel/Nickel didn't do
the job completely.
(I'm going to guess the grayscale flag wasn't getting flipped properly).
* Dither every non-transparent icon to the eInk palette
* Make sure hasBGRFrameBuffer is only enabled when the Kobo fb actually is
@ 32bpp...
* Re-process badly grayscaled icons
* And re-grayscale that one w/ gamma correction so the squares show up
better.
* Allow the fbdepth switch to be disabled (in Developer settings).
Also, allow setting debug mode that way.
Also, forcibly disable verbose logging when disabling debug.
* Update setting name to piggyback on the existing check in reader.lua
* Update icons postprocessing info
