Fix ISO-2022-JP-MS encoding convert

ISO-2022-JP-MS characters are removed by iconv on sending mail.
Use mbstring functions on sending.
Add a unit test.

program/lib/Roundcube/rcube_charset.php

@@ -307,7 +307,7 @@ class rcube_charset
 
         // convert charset using iconv module
         if ($iconv_options !== false && $from != 'UTF7-IMAP' && $to != 'UTF7-IMAP'
-            && $from !== 'ISO-2022-JP'
+            && $from !== 'ISO-2022-JP' && $to !== 'ISO-2022-JP'
         ) {
             // throw an exception if iconv reports an illegal character in input
             // it means that input string has been truncated

tests/Framework/Charset.php

@@ -71,6 +71,7 @@ class Framework_Charset extends PHPUnit_Framework_TestCase
             array('&BCAEMARBBEEESwQ7BDoEOA-', 'Рассылки', 'UTF7-IMAP', 'UTF-8'),
             array('Рассылки', '&BCAEMARBBEEESwQ7BDoEOA-', 'UTF-8', 'UTF7-IMAP'),
             array(base64_decode('GyRCLWo7M3l1OSk2SBsoQg=='), '㈱山﨑工業', 'ISO-2022-JP', 'UTF-8'),
+            array('㈱山﨑工業', base64_decode('GyRCLWo7M3l1OSk2SBsoQg=='), 'UTF-8', 'ISO-2022-JP'),
         );
     }