Merge pull request #538 from chrox/master

add make test in Makefile and README file
Added missing Czech messages, fixed others
Fixed minor glitches
More strings fixed
Synced with Transifex
Merge pull request #539 from dsmid/master

Czech (cs_CZ) l10n updated
Update koreader.po
Merge pull request #540 from th0mass/patch-1

Update koreader.po
Merge pull request #541 from chrox/master

fix wrong screen dpi on Kindle Paperwhite 2
fix infinite loop on up-skip CJK puncutuations