F12 reconnection is not working with language setting other than English

[ruby3141]

Because locating the back button to detect and exit error screen is done by image searching with back.png sample file,
the script would fail to notice disconnection when the back button doesn't show the English word "back" on it.

Pending Actions

• update readme to inform user about using disconnection recovery with language other than English
• (maybe) provide bunch of presampled "back button" to do it more easily
• (maybe) implement GUI for register and change