obj-clean.
This basically entails putting ${.CURDIR} in front of the occasional
source file, script, or directory.
Also adds '.include <bsd.obj.mk>' to web.mk so 'make obj' works.
Change gencommercial script to take a '-s' flag pointing to the source
directory, and the portindex script to take an optional additional
parameter indicating the source directory.
Add -D ${.CURDIR} to sgmlformat to follow includes properly.
index.sgml came from doc/en_US.ISO_8859-1/tutorials/, and is the last
web site specific file to come out of the doc/ repository. They are
now separated.
Makefile is best termed a "gross hack". This will be removed as soon
as the docs are spirited away on to their own web site.