Ticket #8623 (new enhancement)

Description

I suggest to add following code in order to enhance the fields for substitution in templates :

In def add_headers() add the two "#SUBJECT" rows as following :

        extra_content = self.get_extracontent(req)
        extra_content = extra_content.replace('#TITLE', title)
        extra_content = extra_content.replace('#VERSION', version)
        extra_content = extra_content.replace('#DATE', date)
        extra_content = extra_content.replace('#SUBJECT', subject)
        extra_content = extra_content.replace('#USER', req.remote_user)

        if book:
            frontpage = self.get_frontpage(req)
            frontpage = frontpage.replace('#TITLE', title)
            frontpage = frontpage.replace('#VERSION', version)
            frontpage = frontpage.replace('#DATE', date)
            frontpage = frontpage.replace('#SUBJECT', subject)
            frontpage = frontpage.replace('#USER', req.remote_user)