Merge branch 'mn/send-email-works-with-credential'

Hooks the credential system to send-email. * mn/send-email-works-with-credential: git-send-email: use git credential to obtain password Git.pm: add interface for git credential command Git.pm: allow pipes to be closed prior to calling command_close_bidi_pipe Git.pm: refactor command_close_bidi_pipe to use _cmd_close Git.pm: fix example in command_close_bidi_pipe documentation Git.pm: allow command_close_bidi_pipe to be called as method