Enable utf8mb4 charset

issue: #1698

web/templates/admin/add_db.html

@@ -148,6 +148,8 @@
                                         <option value=latin5 <?php if ((!empty($v_charset)) && ( $v_charset == 'latin5')) echo 'selected';?> >latin5</option>
                                         <option value=armscii8 <?php if ((!empty($v_charset)) && ( $v_charset == 'armscii8')) echo 'selected';?> >armscii8</option>
                                         <option value=utf8 <?php if ((!empty($v_charset)) && ( $v_charset == 'utf8')) echo 'selected';?> <?php if (empty($v_charset)) echo 'selected';?> >utf8</option>
+                                        <option value=utf8mb4 <?php if ((!empty($v_charset)) && ( $v_charset == 'utf8mb4')) echo 'selected';?> >utf8mb4</option>
+
                                         <option value=ucs2 <?php if ((!empty($v_charset)) && ( $v_charset == 'ucs2')) echo 'selected';?> >ucs2</option>
                                         <option value=cp866 <?php if ((!empty($v_charset)) && ( $v_charset == 'cp866')) echo 'selected';?> >cp866</option>
                                         <option value=keybcs2 <?php if ((!empty($v_charset)) && ( $v_charset == 'keybcs2')) echo 'selected';?> >keybcs2</option>