fix crash when configuration file is invalid
Merge branch 'dev' of https://github.com/OlafRadicke/peruschim_cpp into dev
forward declare ConfigImpl for better encapsulation - user of Config do not need to know anything about ConfigImpl
when reading configuration fails, propagate error to main instead of just ignoring it
use tntdb::Statement::selectRow and selectValue to read single rows or values
move database stuff from Edition to EditionManager class and other cleanups
issue better error message when configuration file could not be read