Update assetml.in too.
Alexey Lubimov fixes the description in russian assetml alphabet file.
gameutil.c: fix crash when closing dialog with a callback.
click_on_letter: fallback to english if locale sound is not here.
soundutil: add usefull function to get filename  Uxxxx.ogg from letter.
gcompris: fix compilation error with gcc 4.0 (missing declaration)