Added get OS Browser Device and IP functions, added these functions to guest view invoice, also added invoice view alert and other minor fixes

client_side_nav.php

@@ -6,7 +6,7 @@
     <h2 class="text-white text-center"><?php echo $client_name; ?></h2>
     <h6 class="text-secondary text-center"><?php echo $client_type; ?></h6>
   </li>
-  <?php if($session_client_id == 0){ ?>
+  
   <li class="nav-item">
     <a class="nav-link" href="clients.php">
       <button class="btn btn-outline-light btn-block">
@@ -15,7 +15,6 @@
     </button>
     </a>
   </li>
-  <?php } ?>
 
   <li class="nav-item <?php if($_GET['tab'] == "overview") { echo "active"; } ?>">
     <a class="nav-link"