[DO NOT MERGE] Switching between hide window and clear input when pressing 'escape' key

[averissimo]

This is perhaps a very personal workflow, but I expect the text to be cleared when pressing the escape key (closing the window should be with alt+f4 or 'x' button on window)

This preserves history of input, as 'undo' will return previous cleared text

Before merging this PR I have 1 question

1. This option defaults to 'clear input' when 'show icon in tray' is not selected
   • When the window disappears and I see no tray icon it is not obvious to me that the app is still running in background (this is the behavior in Linux/Ubuntu)...

Quesiton for OSX users: do you still see the icon somewhere?

Screenshot below shows that radio buttons are not enabled and defaults to clear input when 'show tray' is not active.

Example

Screencast shows an example of how it works. The option is available in View -> Escape behavior -> Hide window / Clear input radio buttons

ps. I took the screenshots with my dev build that includes @arnriu's link snippet feature and @mliq popup privacy notifications (still dev).. ignore all 'unkown' options seen in screenchot/screencast as they are not included in the PR request