Streamlines the direct debit frontend keys like for the other providers
Adapts tests for direct debit payment provider
Adapts checkout client tests to change of the config keys in the direct debit provider
Merge https://github.com/Arcavias/arcavias-core
Adapts translations for direct debit config keys
Minor coding style improvements
Fixes formatting of status output from setup task
Improves compliance to Iterator interface
Fixes infinite loop in text export when ID and content are empty
Merge pull request #363 from nsendetzky/master

Various bugfixes and improvements