* Documentation/user/lilypond.tely: Add dir entries for

* Documentation/user/lilypond.tely: Add dir entries for
executables.

* Documentation/user/converters.itely:
* Documentation/user/invoking.itexi: Fix `invocation' node names,
in line with standard dir entries.

* Documentation/user/convert-ly.itexi
* Documentation/user/ly2dvi.itexi: Remove.

* scripts/ly2dvi.py: Add pseudo-filter (and stdout output)
support.

* lily/main.c:
* lily/paper-score.cc :
* lily/gourlay-breaking.cc: Write info to stderr.