HNotate

Copperbox revision 249.

Some tidying up of OutputMain the score generation module.

It's still deficient - the evaluation that builds 'plugs' (indexed documents to fill holes in templates) has the generation strategy hard-wired. The generation performs two steps - render to a common format (the score data types) then output to a either LilyPond or Abc. I want it to be able to just render to the common score format for debugging purposes, but to do that will mean so rethinking of the code.