Mark previously-edited messages with "(edited)" (#10)

* Mark previously-edited messages with "(edited)"

* Merge multiple WriteString() to one

util/discord.go

@@ -32,6 +32,10 @@ func WriteMessage(messagesTextView *tview.TextView, session *discordgo.Session,
 		content.WriteString(message.Content)
 	}
 
+	if message.EditedTimestamp != "" {
+		content.WriteString(" [::d](edited)[-:-:-]")
+	}
+
 	// TODO(rigormorrtiss): display the message embed using "special" format
 	if len(message.Embeds) > 0 {
 		content.WriteString("\n<EMBED>")