Merge branch 'maint'

Merge branch 'maint'

* maint:
  Start preparing for 1.5.1.3
  Sanitize @to recipients.
  git-svn: Ignore usernames in URLs in find_by_url
  Document --dry-run and envelope-sender for git-send-email.
  Allow users to optionally specify their envelope sender.
  Ensure clean addresses are always used with Net::SMTP
  Validate @recipients before using it for sendmail and Net::SMTP.
  Perform correct quoting of recipient names.
  Change the scope of the $cc variable as it is not needed outside of send_message.
  Debugging cleanup improvements
  Prefix Dry- to the message status to denote dry-runs.
  Document --dry-run parameter to send-email.
  git-svn: Don't rely on $_ after making a function call
  Fix handle leak in write_tree
  Actually handle some-low memory conditions

Conflicts:

	RelNotes
	git-send-email.perl