How about support XDG dir structure

Instead of useing ~/.onboard, put config files to
$XDG_CONFIG_HOME/signon, cache files to $XDG_CACHE_HOME/signon, data
files to $XDG_DATA_HOME, like the other applications do.

The default fallbacks are:
 $XDG_CACHE_HOME -> $HOME/.cache
 $XDG_CONFIG_HOME -> $HOME/.config
 $XDG_DATA_HOME -> $HOME/.local/share

example: glib contain functions like g_get_user_config_dir(),
g_get_user_cache_dir().

I really hope you can implement this change, it would make the home dir
cleaner, and user can delete all application's cache files or config
files or data files easily.

 Cheers!