Elwig: Rename buchführend, funktionär, volllieferant, and gebunden

Elwig/Models/Entities/Season.cs

@@ -107,7 +107,7 @@ namespace Elwig.Models.Entities {
         [Column("calc_mode")]
         public int CalcMode { get; set; }
         [NotMapped]
-        public bool Billing_HonorGebunden {
+        public bool Billing_HonorContracted {
             get => (CalcMode & 0x1) != 0;
             set => CalcMode = value ? CalcMode | 0x1 : CalcMode & ~0x1;
         }