Currently, install-slashsite automatically chooses
$prefix_site/$sitename/htdocs as the basedir.
The following patch allows users to choose, if they wish, a different basedir for the htdocs. The -b option was added.
Only install-slashsite and Install.pm need to be changed, I believe. I'm not positive there aren't any hidden effects of this, but I doubt it. This is my first time making a patch, so I apologize if I screwed some stuff up. I used diff -u.