add gettext lua module
use gettext in reader.lua
add l10n directory
copy i18n in customupdate
use DroidSansFallback for all major fonts

we need DroidSansFallback for internalization :)
use gettext in readermenu
use gettext in readertoc
add gettext to readermenu
add koreader demo template
rename template folder name
remove debug name
add Makefile for managing po and pot files

basically wrapper around tx
update tx config and koreader template
pull zh translation from transifex
add gettext related target to Makefile
require gettext module in uimanager.lua
add target to generate mo files
Merge pull request #36 from houqp/houqp-master

add gettext support