Refactor HTML templating into module.

Makefile:
	fix cleaning root/www/doc;

kernel/Makefile:
	create root/www/doc/src even if root/www/doc doesn't exist;

util/Template.pm: (ADD)
	moved code from template.pl and txt2html.pl to this reused module.

util/fmtsrc.pl:
	add usage;
	forward all arguments at --template to the Template argument parser;
	use Template.pm to format the content rather than opening a pipe
	to template.pl.

util/template.pl:
	remove most code to Template.pm.

util/txt2html.pl:
	remove template code and TOC generation code to Template.pm and use it.
Doctools: static path fixes

Makefile:
	Use our menu.xml for DOC/%.html;
	use same rule form as for DOC/%.txt;

util/doctools.pl:
	use --relpath and -d values rather than hardcoded DOC/ and doc/.
Web Templates: add --css option
Doctools: difftime path translation
linkchecker: speed & resource improvement
website: fix menu links; js chrome fix

root/www/scene_pack.js:
	TODO: this file is concatenated (source updated);remove file
	and generate on the fly;

	fix javascript syntax: function arguments cannot have default values;

root/www/*menu.xml:
	use href for paths due to the templating -p (relpath) applying it
	to links rather than just to resources.

root/www/index.html:
	load the menu.
	TODO: use template.
Update TODO.