iRel interface updates

[Mark Shephard]

The RPI team will be hitting iRel once things with iMesh and iMeshP are 
more complete.

James Porter wrote:
> There hasn't been much in the way of discussion about the new iRel
> interface, which I'm hoping is a good thing. If I don't hear any
> rumblings about these changes, I'll be making them the "official" iRel
> interface for Lasso early next week (read: I'll merge in my working
> branch).
> 
> - Jim
>