Added csv export functionality

add place for more account numbers and telefon numbers

added places for more account numbers, telefon numbers, fax numbers a…

…nd emails

Blocked email sending if there aren't any buyers and invoices

Blocked email sending if there aren't any buyers and invoices

Blocked email sending if there aren't any buyers and invoices

Added a stamp choice to settings

add organizer with calendar

changed to english variables, functions, classes and files

Code improvement