majalan

Copperbox revision 3207.

I've changed Context to allow user context and removed tuning pitch and amplitude which were mostly superfluous (and added complexity).

For the moment, I've removed Advance's dependency on Context. This simplifies Advance and its current API doesn't need it, but it might be the wrong decision (as a comparison Wumpus threaded Context through everything but then Context was much more important).

As I'm undecided about objects depending on Context, both note lists and thus Demo02 and Demo03 are all currently broken.