append null to avoid message artifacts

src/packet/ship.rs

@@ -274,7 +274,10 @@ pub struct SmallDialog {
 }
 
 impl SmallDialog {
-    pub fn new(msg: String) -> SmallDialog {
+    pub fn new(mut msg: String) -> SmallDialog {
+        if !msg.ends_with('\0') {
+            msg.push('\0');
+        }
         SmallDialog {
             padding: [0; 0x02],
             msg: msg,