On kindle, kobo and pocketbook the data directory is the current
running directory but on Android the app is installed in system
defined location and users may have no access to that location.
The same circumstances should be true for the upcoming Koreader for
Ubuntu touch, so the data directory (in which tessdata, dictionaries,
global settings, persistant defaults and probably history data are
stored) could be stored in another place.
The VFAT file system of `/mnt/us` is case insensitive so that
require("json") from Spore which intends to load luajson module in
rock directory actually will load `frontend/JSON.lua`, the two JSON
parser libraries have slightly different APIs.
This patch remove the pure Lua JSON library in favor of `luajson` which
uses LPeg pattern marching backend for better performance.
The 'KOSync' plugin will synchronize furthest reading progress
across different koreader devices after users registering their
devices.
The synchronizing service is open-sourced as the project
[koreader/koreader-sync-server](https://github.com/koreader/koreader-sync-server).
This is a major overhaul of the hardware abstraction layer.
A few notes:
General platform distinction happens in
frontend/device.lua
which will delegate everything else to
frontend/device/<platform_name>/device.lua
which should extend
frontend/device/generic/device.lua
Screen handling is implemented in
frontend/device/screen.lua
which includes the *functionality* to support device specifics.
Actually setting up the device specific functionality, however,
is done in the device specific setup code in the relevant
device.lua file.
The same goes for input handling.
Now the frontlight remains unchanged from Nickel to koreader and vice
versa.
Also ffi/kobolight.lua has been changed to allow for usage of the toggle
button in the filemanager.
Device:hasFrontlight always returned a true-like value because util.isEmulated was an integer.
Fixed this, also, used a polymorphic object design to reduce FrontLight code, and
adapted BaseFrontLight for the emulator.
