and colors.

	* src/boards/click_on_letter.c: (start_board), (conf_ok):
	* src/boards/colors.c: (conf_ok), (start_board), (end_board): support sound locale.
          now the background music is muted.
	* src/gcompris/board_config.c: (gcompris_get_locales_list),
	(gcompris_get_locales_asset_list): now support $LOCALE in the file to check for.
	* src/gcompris/config.c: (gcompris_config_start),
	(gcompris_get_locale_name), (item_event_ok): added an API entry
	 gcompris_get_locale_name() to return the country name based on a locale name.
	* src/gcompris/gameutil.c: (gcompris_find_absolute_filename): improved to limit searches
	* src/gcompris/gcompris.h: