Active tab highlight override from url hash (#81)

* Create class.settings-api.php

if url has section id as hash then set it as active or override the current local storage value
Here is an exmaple from a practical plugin integration 
wp-admin/options-general.php?page=cbxuseronline#cbxuseronline_dash_widget where #cbxuseronline_dash_widget is id of a section.

* Update class.settings-api.php

variable named fixed for 'activetab'

Author: manchumahara

src/class.settings-api.php

@@ -566,6 +566,15 @@ function script() {
                 if (typeof(localStorage) != 'undefined' ) {
                     activetab = localStorage.getItem("activetab");
                 }
+                
+                //if url has section id as hash then set it as active or override the current local storage value
+                if(window.location.hash){
+                    activetab = window.location.hash;
+                    if (typeof(localStorage) != 'undefined' ) {
+                        localStorage.setItem("activetab", activetab);
+                    }                
+                } 
+                
                 if (activetab != '' && $(activetab).length ) {
                     $(activetab).fadeIn();
                 } else {