Merge changes of repository klaaspeter/achievo

Most additional changes of [klaaspeter/achievo](https://github.com/klaaspeter/achievo) were passed through, but there are still some changes that should be reviewed and (if reasonable) merged. See issue #10!

I've merged everything by cherry picking (```git cherry-pick -n [commit]```), thus reviewed all changes manually. Everything should be fine, ```klaaspeter/achievo``` isn't (logically) ahead anymore. Anyway, all changes need to be tested!