Optionally expose alternative node translation links as fields

Currently, the alternative node translation links are injected into the node's links array, via hook_node_view() (in line 108, entity_translation.node.inc).

However, this makes their placement within the page uneditable short of pulling the links out in the theme template.php and injecting them elsewhere in the node template. What if these links were optionally made available via hook_field_extra_fields() so that the language links could be, for example, placed above the node body (a fairly reasonable thing to want to do).

In the process, it might make sense to abstract some of the code in hook_node_view() so that shared code during link creation can be reused.