Add methods to check whether Message is mentioning User (#323)

src/model/channel/message.rs

@@ -490,6 +490,21 @@ impl Message {
         http::send_message(self.channel_id.0, &map)
     }
 
+    /// Checks whether the message mentions passed [`UserId`].
+    ///
+    /// [`UserId`]: ../../model/id/struct.UserId.html
+    pub fn mentions_user_id<I: Into<UserId>>(&self, id: I) -> bool {
+        let user_id_to_find = id.into();
+        self.mentions.iter().any(|mentioned_user| mentioned_user.id.0 == user_id_to_find.0)
+    }
+
+    /// Checks whether the message mentions passed [`User`].
+    ///
+    /// [`User`]: ../user/struct.User.html
+    pub fn mentions_user(&self, user: &User) -> bool {
+        self.mentions_user_id(user.id)
+    }
+
     /// Unpins the message from its channel.
     ///
     /// **Note**: Requires the [Manage Messages] permission.