Add 'edit'-operation on panes overview.

Right now, if a user is on the Commerce Extra Panes overview page (admin/commerce/config/checkout/extra) and wants to edit one of the nodes used as pane content, that user will need to go to the manage content screen, find the node and edit it. It would be great if you could edit the node straight from the overview page. Note that the contextual links on checkout itself already link to node/%/edit for the Commerce Extra Panes pane.

Patch attached adds the "edit"-operation to the list of operations on the overview page, provided the user has permissions to edit the node: