improve the email template [img_] tag, fixes some path issues when emailing from plugins by allowing the path to be relative to the base of the install. Modified default templates, but fixed the code to support the old paths with directory shifts as well to avoid having to modify site_text in existing installs

git-svn-id: http://svn.montala.net/svn/resourcespace@4328 c08608d7-6e46-0410-86ca-f2a6f1370df5