Added support for custom bill items.
These are needed for additional items on bills like "Soli-Beitrag" etc. that are not subscription related.
Custom bill item types ("Rechnungsextra") can be defined in admin.
Bills may be modified in admin by adding custom items using one of the defined types.
The custom item type also specifies the booking account for use in bookings export.
Added support for custom bill items. These are needed for additional items on bills like "Soli-Beitrag" etc. that are not subscription related.
Custom bill item types ("Rechnungsextra") can be defined in admin. Bills may be modified in admin by adding custom items using one of the defined types. The custom item type also specifies the booking account for use in bookings export.
Has migrations.