use `bind` instead of hardcoding cwine

I really didn't like how the cwine movement functions needed to refer to
cwine directly. `bind` (or `call`) is the solution I was looking for.
Now cwine could theoretically be cloned if needed.
render paths between panels

I added several new pieces of cwine to accomplish this:

1. cwine.indices is a hash to link panel ids to their index in the
   cwine.panels array
2. cwine.panelGroup and cwine.pathsGroup were added to the cwine.layer
   rather than adding all objects directly to the cwine.layer
3. cwine.loadPanels takes the cwine object to prevent looping through
   the panels again. this approach seems dirty though.