Developer credits in 4.2

[Daichi Kawahata]

Hi,

I've updated credits file in 4.2 branch, in which Graf is moved to
the core developers section (because he has his application in core
module), if I was wrong on that or there're still missing credits in
developer-wise, that'd be your task, please correct/add it.

As for the 4.2.3, while there're still something to do (additional
strings in xfce-utils/xfce4-about/AUTHORS.$lang/html.$lang, final
po/ChangeLog updates), I can say it'd be ready to release, changes
from previous release will be:

General:

  * New languages (in ISO 639 language code order):

    Afrikaans (af), Armenian (hy), Slovenian (sl).

  * New documentation:

    Hebrew (he).

  * Updated languages (in ISO 639 language code order):

    Belorussian (be), Catalan (ca), Greek (el), Esperanto (eo),
    Basque (eu), Finnish (fi), Hebrew (he), Italian (it), Japanese (ja),
    Korean (ko), Lithuanian (lt), Dutch (nl), Polish (pl), Brazilian
    Portuguese (pt_BR), Romanian (ro), Swedish (sv), Traditional Chinese
    (zh_TW).

Regards,
-- 
Daichi

Language Codes: http://www.w3.org/WAI/ER/IG/ert/iso639.htm
Country Codes: http://www.ics.uci.edu/pub/ietf/http/related/iso3166.txt