.mailmap: Combine more (email, name) to individual persons

I got more responses from people regarding the .mailmap file.
All added persons gave permission to add them to the .mailmap file.

It's mostly email mappings again. However we also have Nick Stokoe,
who contributed as Nick Woolley. He changed his name, but kept the email.

Signed-off-by: Stefan Beller <stefanbeller@googlemail.com>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>