Support right-clicking links

[neocotic]

As suggested by serpa here right-clicking on links should be supported by adding a context menu similar to the structure in the popup.

However, template data like title might not make as much sense. Should these be the text of the link, the current page title, or simply the same as source? What if the link contains no text (e.g. empty or an img)?

Investigation will need to be carried out to ensure context menu items can be populated dynamically as it will need to be in order to be used by this extension.

[neocotic]

Support for context-menus has now been added and it works perfectly.