Fix Bookmarks modal not closing on ESC

[objectliteral]

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[makew0rld]

Thanks! I didn't think of this, but it's handy. Could you add this for other modals too? And update help.go as well to note that Esc will exit modals.

Self-note: Update wiki about this as well.

[objectliteral]

AFAICT all the other modals already close on ESC. I tested it specifically for the Subscription and Input modal. The code for the other modals also seems like they should close.

Note added to help.go as well.

[makew0rld]

Thanks!