style: DMs only take up 80% of screen width

DMs now take up only 80% of the available screen width so it looks much
more like iMessages.

Closes: #286
Changelog-Changed: Make DMs only take up 80% of screen width

damus/Views/DMView.swift

@@ -18,7 +18,7 @@ struct DMView: View {
     var body: some View {
         HStack {
             if is_ours {
-                Spacer()
+                Spacer(minLength: UIScreen.main.bounds.width * 0.2)
             }
 
             let should_show_img = should_show_images(contacts: damus_state.contacts, ev: event, our_pubkey: damus_state.pubkey)
@@ -29,6 +29,9 @@ struct DMView: View {
                 .background(is_ours ? Color.accentColor : Color.secondary.opacity(0.15))
                 .cornerRadius(8.0)
                 .tint(is_ours ? Color.white : Color.accentColor)
+            if !is_ours {
+                Spacer(minLength: UIScreen.main.bounds.width * 0.2)
+            }
         }
     }
 }