[Jtcfrost-devl] Open Selected Key / Attachment in Browser

[artur <ar...@gm...>]

Hi,

here is another small patch.
It allows to open a link or attachment in the system default browser.
This only works when the URL prefix under the options/misc menu is 
configured. If this option is empty, no URL will be opened (for safety / 
information leak).

Cheers

artur