Make ordering links term context sensitive

The ordering links on the bottom of nodes quickly become unwieldy when a node is in multiple terms. Also, it makes little sense to see the ordering links for other terms when the node is being viewed in a taxonomy/term/x (or nodeorder/term/x) page, or for any terms when it's being viewed by itself.

Attached is a patch that makes the ordering links appear only in the context of taxonomy/term/x and nodeorder/term/x pages, and only ordering links for the term being displayed. It updates the link text (just "Move up/down") and description ("Move [node title] up/down in this category") accordingly.

The term context is determined from the path. While this is not ideal, there doesn't seem to be any other method (let me know if you know of something better!) because hook_link() doesn't provide any term information. Perhaps the links could be displayed with something other than hook_link(), but I'm not sure. The method currently used works with aliases (and therefore pathauto).