Replace deprecated instr function with str_contains and add include/global.php for central configurations.

include/modal_wait.html

@@ -5,7 +5,7 @@
     <div class="modal-content">
       <div class="modal-header">
         <h4 class="modal-title mb-1 text-dark text-uppercase">
-          <center><i class="bi bi-hourglass-split"></i><br> Work in progress ...</center>
+          <span class="text-center"><i class="bi bi-hourglass-split"></i><br> Work in progress ...</span>
         </h4>
       </div>
       <div class="modal-body">