relative url for internal anchors and images

[Anguz]

I know that the full boardurl is needed to be used in email messages with a link to the forum, but inside the forum's pages, urls relative to the root are better

for one, they seem to be better spidered by the search engines - the relative one is obviously inside the website, the full one needs to be checked and I don't know if it is

second, it lets one use multiple domains for the community without going to the domain in settings

the change could be easy, save the full boardurl in a new var and use this one in the emails, and change the value of the var used for the pages to just the forum's path without the domain

I know it can be done as a mod,  but if it's something pretty simple, it'd be good that it's included

mods will be written based on the clean install and it'll be harder in the future to make the change, even with a mod, due the incompatibilities that may/will happen