merge in 2.16.1 source chagnes

diff --cc Documentation/changes.tely
Simple merge

diff --cc Documentation/cs/learning.tely
Simple merge

diff --cc Documentation/de/web.texi
Simple merge

diff --cc Documentation/es/changes.tely
Simple merge

diff --cc Documentation/it/learning.tely
Simple merge

diff --cc Documentation/music-glossary.tely
Simple merge