Update signup and functions

content/signup.php

 Design::header($setup, 0);
 
 if (isset($_POST['username'])) {
-    Alter::addUser($_POST['username'],$_POST['password'],$_POST['realname'],$_POST['mail'],25);
+    if (Alter::addUser($_POST['username'],$_POST['password'],$_POST['realname'],$_POST['mail'],25)) {
+     // Success! User created - Redirect to login
+        header('Location: ' . Config::$sys_url . '?page=login');
+    } else {
+        // Aww, signup failed!
+        $success = false;
+    }
 }
 ?>
 
     <h1>Opret Bruger</h1>
     <div class="border"></div>
     <br />
-
     <div class="contactform">
         <form method="POST" action="?page=signup">
+            <?php if (isset($success)) {
+             // If $success is defined, we know we failed.
+                echo "<p>Der skete en fejl, prøv igen!</p>";
+            }
+            ?>
             <div class="form-control">
                 <label>Brugernavn: </label>
-                <input class="inputfield"  type="text" name="username" placeholder="Brugernavn" required minlength="3" />
+                <input class="inputfield"  type="text" name="username" placeholder="Brugernavn" <?php if (isset($success)) { echo 'value="' . $_POST['username'] . '"'; } ?> required minlength="3" />
             </div>
             <div class="form-control">
                 <label>Password: </label>
             </div>
             <div class="form-control">
                 <label>Fuldt navn: </label>
-                <input class="inputfield"  type="text" name="realname" placeholder="Fuldt navn" required minlength="5" />
+                <input class="inputfield"  type="text" name="realname" placeholder="Fuldt navn" <?php if (isset($success)) { echo 'value="' . $_POST['realname'] . '"'; } ?> required minlength="5" />
             </div>
             
             <div class="form-control">
                 <label>E-mail: </label>
-                <input class="inputfield"  type="email" name="mail" placeholder="E-mail adresse" required minlength="5" />
+                <input class="inputfield"  type="email" name="mail" placeholder="E-mail adresse" <?php if (isset($success)) { echo 'value="' . $_POST['mail'] . '"'; } ?> required minlength="5" />
             </div>