XHTML strict. Fix entity.

filter/tex/filterconfig.html

@@ -22,8 +22,8 @@
     $txt->pathlatex = get_string( 'pathlatex','admin' );
     $txt->pathdvips = get_string( 'pathdvips','admin' );
     $txt->pathconvert = get_string( 'pathconvert','admin' );
-    $txt->tick = '&#x2714';
-    $txt->cross = '&#x2718';
+    $txt->tick = '✔';
+    $txt->cross = '✘';
 
     // check file exists & display tick or cross 
     function texbinaryconfirm( $path ) {