Reorganization of Docs

[Carl D. Sorensen]

I am working on a reorganization of LM6 Programming Interfaces.

One section is on Internal representations.

I have a section on displaying Scheme representations, and I want to add a
section on displaying LilyPond representations.

I propose that section 3.3.4. Displaying LilyPond notation move to LM 6.

I have copied this material to the new version of LM6.  I have not yet
removed it from 3.3.4.  I have a different node name so both sections can
coexist in the meantime.

Thanks,

Carl