initial scaffolding for inverted, custom message list

src/models/message.vala

@@ -0,0 +1,16 @@
+using GLib;
+
+public class Message : Object 
+{
+    public string guid { get; set; default = ""; }
+    public string content { get; set; default = ""; }
+    public int64 date { get; set; default = 0; }
+    public string?sender { get; set; default = null; }
+
+    public Message.from_hash_table(HashTable<string, Variant> message_data) {
+        guid = message_data["guid"].get_string();
+        content = message_data["content"].get_string();
+        date = message_data["date"].get_int64();
+        sender = message_data["sender"].get_string();
+    }
+}