ochre

Copperbox revision 2830.

I've redesigned the phantom type layer in Ochre so it works the same as Wumpus-Expr.

As a side-effect I've coined my own alternative to the do-notation for handling effects. Ideally I would have used the do-notation but I need to reify pure let-binding as well as monadic binding. Interestingly Csound instruments more-or-less have their own do-notation separating pure expressions and effects - pure expressions bind with equals, effects bind with calls to opcodes which are just missing (<-)  in the syntax.