client: Started working on ability to sync messages after last known message

kordophone/src/model/message.rs

@@ -2,6 +2,10 @@ use serde::Deserialize;
 use time::OffsetDateTime; 
 use uuid::Uuid;
 
+use super::Identifiable;
+
+pub type MessageID = <Message as Identifiable>::ID;
+
 #[derive(Debug, Clone, Deserialize)]
 pub struct Message {
     pub guid: String, 
@@ -22,6 +26,14 @@ impl Message {
     }
 }
 
+impl Identifiable for Message {
+    type ID = String;
+
+    fn id(&self) -> &Self::ID {
+        &self.guid
+    }
+}
+
 #[derive(Default)]
 pub struct MessageBuilder {
     guid: Option<String>,