i18n/reader: implement changeable UI language
add config.js to .gitignore

followup to 713f28fbd006da668919f564b7296135282d7b4a
updated english i18n
fix relaying of arrow keys
make the modal box itemizable to support different modals
using the new modular modals infrastructure, bark on all IE versions as well as on Safari win32.

IE can't work because iframes don't allow data: URIs, and win32 Safari completely misses CSS3 calc().

Todo: Is it worth the effort to work around missing calc() support?
Merge branch 'master' into HEAD
de i18n: fix typo resulting in invalid JS
CSS: style up the library a bit...
fix missing output in error message