NRFE-189: link .html file ending, since regain does not support XHTML without file endings

See http://forum.murfman.de/de/viewtopic.php?f=13&t=1200
NRFE-189: add support for inserting custom html in the html top, show last update
NRFE-189: adjust issue html; make issue links local
NRFE-189: check if issue is correct
NRFE-189: mention gigan
NRFE-189: only update projects with modifications since last export