git-p4.py: add support for filetype change

git-p4.py: add support for filetype change

After changing the type of a file in the git repository, it is not possible to
"git p4 publish" the commit to perforce. This is due to the fact that the git
"T" status is not handled in git-p4.py. This can typically occur when replacing
an existing file with a symbolic link.

The "T" modifier is now supported in git-p4.py. When a file type has changed,
inform perforce with the "p4 edit -f auto" command.

Signed-off-by: Romain Picard <romain.picard@oakbits.com>
Acked-by: Luke Diamand <luke@diamand.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>