* Use a CRe set* method when toggling nightmode
This ensures it gets flagged as add_reset by the call cache, and that
CRe will actually re-render, as it's necessary if nightmode_images is
enabled (the default).
Fix#6845
* Prevent ReaderHighlight:onTap from running ReaderHighlight:clear when
it's unnecessary.
Avoiding a clearSelection call in CRe that could invalidate the cache
and cause unnecessary redraws.
* Don't store empty highlight arrays when all HLs on a page have
been deleted