Add class MD_JAIL for forcing coders to set time and memory limits

exceptions/MDJailSecurityOptionNotSetException.php

@@ -0,0 +1,21 @@
+<?PHP
+declare(strict_types = 1);
+
+/**
+ * Exception thrown by MDJail if a required security option has not been set.
+ */
+final class MDJailSecurityOptionNotSetException extends Exception {
+
+    /**
+     * Error message.
+     *
+     * @return string
+     */
+    public function errorMessage() {
+        //error message
+        $errorMsg = 'A security option of MD_JAIL has not been set: <b>' . $this->getMessage() . '</b>).';
+        return $errorMsg;
+
+    }
+
+}