Elwig: Rename buchführend, funktionär, volllieferant, and gebunden

Elwig/Windows/DeliveryAdminWindow.xaml

@@ -682,7 +682,7 @@
                               Margin="0,70,10,10" Grid.Column="1"
                               DisplayMemberPath="Name"/>
 
-                    <CheckBox x:Name="GebundenInput" IsChecked="{Binding IsGebunden, Mode=TwoWay}"
+                    <CheckBox x:Name="ContractedInput" IsChecked="{Binding IsContracted, Mode=TwoWay}"
                               Content="Gebunden" Margin="10,105,0,0" Grid.Column="0" Grid.ColumnSpan="2" IsThreeState="True"
                               VerticalAlignment="Top" HorizontalAlignment="Left"
                               Checked="CheckBox_Changed" Unchecked="CheckBox_Changed" Indeterminate="CheckBox_Changed"/>