Vertragsbezogene Rechnungen (Schornsteinfeger nicht reingelassen)

[klawr]

Created by: klawr

Problem Description
There is no possibility to assign extra costs to single Vertraege, but this is necessary for a proper assignment of some Umlagen.

Proposed Solution
Add an extra table for VertragsbezogeneRechnungen which assigns costs not to a Wohnung (incl. Year etc.), but to a Vertrag.
This should be transparent to the user. The distinction between Rechnungen for a Wohnung and a Vertrag should be clear, but shouldn't require mental gymnastics to get the intention.