Add option to make comments invisible (not having to delete them). This is for moderation purposes.

includes/comments_db.sql

@@ -2,6 +2,7 @@ CREATE TABLE comments (
 	id INT(11) NOT NULL AUTO_INCREMENT,
     username VARCHAR(255) NOT NULL,
     content TEXT NOT NULL,
+    visible BOOLEAN DEFAULT 1,
     date_sent DATETIME DEFAULT CURRENT_TIME,
     users_id INT(11) NOT NULL,
     PRIMARY KEY (id),