Open With Long-Click

This is an extended version of Lex1's open-in-background-with-long-press extension. It opens links in the background when you click and hold the mouse button for a short time.

Additions from Lex1's extension:
- The amount of time required to trigger a long click can be configured.
- Links can be configured to open in the foreground.
- The extension can be configured to not open duplicate tabs.
- Tabs opened from private tabs will be opened as private. Due to Opera's pop-up blocker, long-clicks in private tabs will activate upon releasing the mouse button instead of immediately like in normal tabs. A small circle will appear around the mouse to indicate that a long-click is triggered and releasing the mouse button will open the link.

Known Issues: (Ignore these for Opera 12.00+)
- Private tab detection currently relies on a bug in Opera, so future updates to Opera may make the extension unable to detect private tabs.
- Opening tabs in the background from private tabs requires opera:config#UserPrefs|Allowscripttoraisewindow to be checked.