Typographic improvements to darkfish

This is a work in progress.  HTML body text styles are improved but the
sidebars and method/constant/attribute display is incomplete.
Fix horizontal rule test
Fix remaining tests
Update markup for index page
Improve consistency of sidebar and first header
Fix placement of sidebar
Better match table of contents to other pages
Remove bullets from table of contents
Update footer to reflect new Darkfish origins

After consulting Michael Granger he agreed I could continue to use the
Darkfish name in RDoc.  As this re-design is derivative I have updated
the footer text to indicate that.
Integrate example output into documentation
Reduce list item margins
Improve wording in markup output examples