Billing: Add functionality to collapse curves

Elwig/Models/Entities/WineAttr.cs

@@ -23,6 +23,13 @@ namespace Elwig.Models.Entities {
         [Column("fill_lower")]
         public int FillLower { get; set; }
 
+        public WineAttr() { }
+
+        public WineAttr(string attrId, string name) {
+            AttrId = attrId;
+            Name = name;
+        }
+
         public override string ToString() {
             return Name;
         }

Elwig/Models/Entities/WineVar.cs

@@ -21,6 +21,13 @@ namespace Elwig.Models.Entities {
         public bool IsRed => Type == "R";
         public bool IsWhite => Type == "W";
 
+        public WineVar() { }
+
+        public WineVar(string sortId, string name) {
+            SortId = sortId;
+            Name = name;
+        }
+
         public override string ToString() {
             return Name;
         }