git-blame --porcelain

git-blame --porcelain

The new option makes the command's native output format to emit
output that is easier to handle by Porcelain.

Each line is output after a header.  The header at the minimum
has the first line which has:

 - 40-byte SHA-1 of the commit the line is attributed to;

 - the line number of the line in the original file;

 - the line number of the line in the final file;

 - on a line that starts a group of line from a different commit
   than the previous one, the number of lines in this group.  On
   subsequent lines this field is absent.

This header line is followed by the following information once
for each commit:

 - author name ("author"), email ("author-mail"), time
   ("author-time"), and timezone ("author-tz"); similarly for
   committer.

 - filename in the commit the line is attributed to.

 - the first line of the commit log message ("summary").

The contents of the actual line is output after the above
header, prefixed by a TAB. This is to allow adding more header
elements later.

Signed-off-by: Junio C Hamano <junkio@cox.net>