v1.4.2: No more dependency of System Events

Update sample image so it reflects current look

Me and @theseal discussed that the sample doesn't look at all like it
does now since we since a couple of years use the Terminal icon and not
the caution icon.

v.1.4.1: Better handling of non-english languages 🇫🇷

v1.4.1

Update ssh-askpass

v1.4.0: Add timeout to confirmation prompt

We need to error out because otherwise we just continue execution and
don't get in the "on error" clean up.

Add SUDO_ASKPASS to environment variables

Alsö also, set DISPLAY to something nonsensical to avoid the possibility of setting it to a valid but undesired value. (E.g., if another user is logged in and has `DISPLAY=0`, but the current user doesn’t have XQuartz running, we don’t want to inadvertantly tell this user’s X apps to appear on the other user’s XQuartz. Or, Xvnc &c.)

Always use System Events

return nothing when we have nothing to return

AFAIK there is no way to set a variable to nothing (null is still null).
So check in the else return nothing.

return "" also returns an empty string including a newline.

v1.2.3: Use System Events only for passwords and pins

But not for OK/Cancel dialog. Using "System Events" has the draw back
that if you're writing an URL in Firefox and ssh-askpass runs "System
Events" dialog doesn't give back focus to where you were, e.g. the URL
bar in Firefox. Using frontmost_application does give back focus where
you were.

We should find a way to test if frontmost_application has support for
AppleScript, IIRC MS Outlook doesn't, and if not fall back to "System
Events".

Resolves #30