osx: implements quicklook

osx/kordophone2/Models.swift

@@ -115,7 +115,15 @@ enum Display
         var previewPath: String {
             data.previewPath
         }
-        
+
+        var isFullsizeDownloaded: Bool {
+            data.isDownloaded
+        }
+
+        var fullsizePath: String {
+            data.path
+        }
+
         init(from serialized: Serialized.Attachment, dateSent: Date, sender: Sender) {
             self.id = serialized.guid
             self.sender = sender