Send pdf invoce with confirmation

Change-Id: Ie5b7b20043d11879f758af6536b55961314188eb
diff --git a/User.php b/User.php
index 5e8487e..91cfa21 100644
--- a/User.php
+++ b/User.php
@@ -3,6 +3,7 @@
 
 class User
 {
+    public $id;
     public $username;
     public $first_name;
     public $last_name;
@@ -23,10 +24,14 @@
     public $participation_confirmed_at;
     public bool $student;
     public bool $conference_dinner;
+    public $registered_at;
+    public bool $earlybird_registration;
     public float $total_due;
+    public $invoice;
 
     function __construct()
     {
+        $this->id = "";
         $this->username = "";
         $this->first_name = "";
         $this->last_name = "";
@@ -47,7 +52,10 @@
         $this->participation_confirmed_at = "";
         $this->student = false;
         $this->conference_dinner = false;
+        $this->registered_at = date("Y-m-d H:i:s") . "UTC";
+        $this->earlybird_registration = false;
         $this->total_due = 0.0;
+        $this->invoice = "";
     }
 
     function __construct1(object $data)
@@ -97,6 +105,7 @@
     function to_string()
     {
         $tmp_user = $this;
+        $tmp_user->invoice = "";
         $tmp_user->password = "***";
         $tmp_user->user_hash = "***";
         return  json_encode($tmp_user);
@@ -113,7 +122,7 @@
     function to_table() {
         $table = "<table  style='border: 1px solid #e1e4e8; border-collapse: collapse; width: 100%;'>";
         foreach ($this as $key => $value) {
-            if ($key != "password" && $key != "user_hash" && !empty($value)) {
+            if ($key != "password" && $key != "user_hash" && !empty($value) && $key != "invoice") {
                 if (is_bool($value)) {
                     if ($value) $value = "yes";
                     else $value = "no";