Add option to hide (skip) non-linear fragments, only working
in 1-page mode. Tweaks mostly to footer, toc and skim code
to make it clear(er) which pages belong to linear or non-linear
fragments.
* 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
Avoid drawing the fill bar our of the progress bar.
Avoid zero divided by zero that return 'nan' (Not a Number),
that does not bother lua code, but will crash libblitbuffer.so
when it gets nan as a coordinate.
* footer(optimize): remove dead code
* footer(fix): disable auto refresh time option when current time is not checked
* fix: support disable progress bar again
colors were a mixture of 4bpp integers (0=white, 15=black) and
fractional blackness levels (0=white, 1.0=black) before. This is
now unified to use the color specification of the Blitbuffer API.
As well as the width of the toc notches
Lower the default value of the container size a bit to avoid eating into
the last line on small borders setup (I checked on 167 & 212 DPI
devices, Feel free to revert to the previous value (19) if that causes
trouble).
