Tweak/unbreak my CPUFreq experiment (koreader#4119)

* Only switch to ondemand when we actually can, and when it's better than the current governor...
  This potentially leaves Mk.5 in the lurch, but there's no perfect solution there :/.

* Switch to UI for the unmark event of navigation hints markers
Might help on non-REAGL devices, and doesn't hurt there (re koreader#3983).

* Switch SQLite DBs to WAL
Sounds nice in theory, behaves fine in practice.

Fix unit tests after crengine update (koreader#3993)

bump base for: [fix, build] AppImage use `-mtune=generic -march=x86-6…

…4` (koreader#3867)

Fixes koreader#3853.

[build] AppImage: support creation in Docker container (koreader#3852)

device/kobo/powerd: Read natural light configuration

Define 'frontlight_settings' table for all Kobo devices, and read
configuration from settings file.

frontlightwidget: Add widgets for changing 'warmth' if available

If the device supports natural light (currently only KA1), extend the
frontlight widget to also allow for changing the 'warmth' value. We
more or less duplicate the widget for 'brightness', with the exception
that we drop the 'toggle' button, which does not make much sense for
the frontlight's warmth. Also, we add captions 'Brightness' and
'Warmth' for clarity.

HTML dict: fix continuous scroll with tap (koreader#3587)

Bump base (sdcv -u patch and framebuffer setViewport dynamically fix) (…

…koreader#3404)

Revert 2 commits that caused crengine scroll mode side effects (korea…

…der#3295)

394be8a (koreader#2855) and 2b3b310 (koreader#3183) introduced side effects (scroll mode
crashing and TOC being reset and rebuild). This reverts parts of them
not yet reverted.

Bump android-luajit-launcher

* Sync LuaJIT with koreader-base at v2.1.0-beta2 koreader/android-luajit-launcher#58