ochre

Copperbox revision 2757.

More work on built-ins.

Csound's built-in functions like abs and the trig functions have quite a nice implementation - as they are monomorphic we can overload them in Haskell and still generate good types in the embedded language. Unfortunately opcodes don't work as well - we need a class per opcode if we want overloading. At the moment we use subscripts on the opcode name instead - an opcode ends in A if it generates an A-rate signal, K if it generates a K-rate signal.