ochre

Copperbox revision 2776.

I've implemented the base opcodes - base is an arbitrary grouping that I happened to use for Ochre's predecessor Orchsyn, basically they are the Math opertations on pages 704 and 705 of the Csound book.

Implementing these opcodes has flagged up some problems in Ochre's type system. Ochre should really be monomorphic, though it is a bit tricksy as it doesn't have a type dictionary - opcodes can cheat and have different typings according to how they are used in the host language Haskell (as the embedding of Ochre borrows some of Haskell's polymorphism).

Ideally I should give opcodes concrete monomorphic types and probably recover Csound's limited polymorphism by duplicating opcodes for different types.