add OpenURL interface hooks

[simon]

OpenURL allows us to add a "Find in Your Library" feature to items. Most major colleges and universities offer an OpenURL resolver, which looks up metadata in a centralized database and determines which databases can provide access to a given resource. More information is available on the ​Ex Libris site. An example OpenURL request (in 0.1 format at George Mason) can be seen ​here.

To add OpenURL lookup support to Scholar for Firefox, we need to add a preference option for what OpenURL resolver to use and which version of OpenURL to use (0.1 or 1.0). These preferences are available through Scholar.Prefs as openURL.resolver (a base URL) and openURL.version (either 0.1 or 1.0).

OCLC provides a publicly-accessible database that we can use to look up the appropriate OpenURL resolver using the user's IP address. Scholar.OpenURL.discoverResolvers() queries this database, and returns an associative array. The key is the institution name; the value is an array containing base URL and version.

We also need a "Find in Your Library" button or menu item in the item pane. How to implement this is up to you. If you want to use it, the OpenURL registry would also let me retrieve a field for an image associated with a given OpenURL resolver (for George Mason, it's ​this), but that might add a bit of clutter to the interface. When this button is clicked, the browser should go to the URL obtained from Scholar.OpenURL.resolve(item).

[david]

(In [445]) Closes #172, add preference for EndNote MIME type stealing feature
Addresses #169, add OpenURL interface hooks
Addresses #170, Put "Link" option before "Import" in drop-down menu

Fixes some advanced search flaws (there are still bugs)

[simon]

(In [447]) references #169, add OpenURL interface hooks

Scholar.OpenURL.discoverResolvers() now returns an array of {name, url, version} objects

[david]

(In [518]) Closes #169, add OpenURL interface hooks

• Added menu, uses OCLC database. (someone should test from GMU or another institution)