git notes support

[JPA2015]

git offers the possibility to supplement a commit message without changing the commit itself using git-notes. "git log" shows such notes along with the original commit message.
It would be nice to have a prepopulated variable with the notes for each commit so that it can be used to generate a change log.

* commits
 - (...)
 - message (The full message)
 - messageNotes (The notes corresponding to this commit)     <=== This could be the new variable
 - (...)