Typewriter: when the user makes multiple typing diff edits, record one of them in the metadata along with an 'and other edits' message. This should get rid of the unspecific 'Typing' metadata you sometimes get

git-svn-id: http://svn.gna.org/svn/etoile/trunk/Etoile/Frameworks/CoreObject@10564 7b3f36aa-e6db-49c1-8b4c-66eac1997e64