majalan

Copperbox revision 2859.

Work towards interpolating "columns" in event lists. The idea was to have parametrize the Event type so it could have a payload as either a normal list of params or a function from an interpolating value to a list of params - but I don't think this is practical. I suspect using a symbolic number type and overloading the Num classes will be simpler.

Copperbox revision 2860.

I've reverted the interpolation changes from the last commit, but kept in the changes that implement advancing c.f advance vectors in computer typesetting and Csound's (+) symbol in score files.