warnings during `make web'

[Werner LEMBERG]

Consider the test file apply-output.ly.  During `make web', extended
debugging is active, and processing the file gives this warning:

  programming error: Grob `NoteHead' has no interface for property `text'
  continuing, cross fingers

Indeed, we are changing the note heads from glyphs to text strings,
and the definition of the NoteHead grob description in
define-grobs.scm doesn't contain `text-interface' (for good reasons
IMHO).

Since my Scheme knowledge is very limited, I wonder whether there
exists an easy method to get rid of this warning: How can I add
`text-interface' to the NoteHead grob temporarily?

There are many other warnings similar to this, and I think it would be
good to fix them all.


    Werner