[bug] Ambitus broken as of 2.5.2

[Juergen Reuter]

Hi!

On the lilypond.org website, in section 5.11.7 of the notation manual, 
version 2.5.2, ambitus does not show noteheads.  Maybe, this is also 
related to the introduction of the symmetric/up/down noteheads in 2.5.2?

BTW., not only my Latin dictionary, but also Webster's says that the 
plural of "ambitus" is "ambitus" (with long "u"), not "ambits".

Greetings,
Jürgen