feat: Calc -> convert transactions with a different currency to the currency of the object to be calculated

feat: UserData -> auto-insert contact person email address when selecting contact person via address

fix: UserData -> set all unset attributes to false instead of undefined; always trigger change on customer select; fix: address select load correct address

refactor: UserData -> show placeholders for contact person / mail; do not auto-fill contact person / mail

fix: workaround for composer bug - Uncaught TypeError: rtrim() expects parameter 1 to be string, bool given