paid invoices support

CebelcaAPISharp.cs

@@ -39,7 +39,7 @@ namespace CebelcaAPI
       }
     }
 
-        public async Task<string> AddInvoiceHead(string partnerId, string idDocumentExt, DateTime dateSent, DateTime dateServed, DateTime dateToPay)
+    public async Task<string> AddInvoiceHead(string partnerId, string idDocumentExt, DateTime dateSent, DateTime dateServed, DateTime dateToPay, bool paid = false)
     {
       Thread.CurrentThread.CurrentCulture = new CultureInfo("sl-SI");
       var values = new Dictionary<string, string>
@@ -50,6 +50,11 @@ namespace CebelcaAPI
                 { "id_partner", partnerId },
                 { "id_document_ext", idDocumentExt }
             };
+      if (paid)
+      {
+        values.Add("payment", "paid");
+        values.Add("payment_act", "1");
+      }
       var ret = await APICall("invoice-sent", "insert-smart-2", values);
       var json = JArray.Parse(ret);
       var retname = (json[0][0] as JObject).Properties().First().Name;