Fix so exported vCard specifies encoding in v3-compatible format (#1489183)

CHANGELOG

@@ -1,6 +1,7 @@
 CHANGELOG Roundcube Webmail
 ===========================
 
+- Fix so exported vCard specifies encoding in v3-compatible format (#1489183)
 - Fix session issues when local and database time differs (#1486132)
 - Fix thread cache syncronization/validation (#1489028)
 - Add option show_real_foldernames to disable localization of special folders

program/lib/Roundcube/rcube_vcard.php

@@ -714,11 +714,17 @@ class rcube_vcard
                             $value[] = $attrvalues;
                         }
                         else if (is_bool($attrvalues)) {
-                            // true means just tag, not tag=value, as in PHOTO;BASE64:...
+                            // true means just a tag, not tag=value, as in PHOTO;BASE64:...
                             if ($attrvalues) {
+                                // vCard v3 uses ENCODING=B (#1489183)
+                                if ($attrname == 'base64') {
+                                    $attr .= ";ENCODING=B";
+                                }
+                                else {
                                     $attr .= strtoupper(";$attrname");
                                 }
                             }
+                        }
                         else {
                             foreach((array)$attrvalues as $attrvalue) {
                                 $attr .= strtoupper(";$attrname=") . self::vcard_quote($attrvalue, ',');