fixed bug: added checks in addInvoice and addRoom
added some translations
added translations
changed stylesheet: warnings atop now
added db.php to gitignore
fixed bug in distribution man which occured, when no rooms were set
fixed bug: flat size was updated only after reload
fixed bug: initializing flatmates array
altered default description of new distribution
added link to distribution manager to invoice manager, if no
distributions present
added a translation
corrected translation