I opted for a capital A (Shift + A) since it seems less likely that
a user would press that shortcut unintentionally compared to just 'a'
without any modifiers.
Added help and de_DE translation for new shortcut
Fixes#629: After using keyboard hotkey (j, k) to navigate to a story on the
unread list and opening the story with "v", the next unread item is now
selected so that the current position won't be lost and the user doesn't have
to start from the top of the list again.
