Doesn't really affect the pages on the web, but it's easier to
preview them in the filesystem when linked to "../main.css" rather
than "/main.css".
The common portion of the <head> section is now in a separate
"include" file.
Added some indentation to masthead/topnav/sidenav so it looks nicer
in the merged source listing.
A bit of Javascript was used to remove the hamburger icon when a
page doesn't have a #sidenav. This worked when sidenav-incl was
being loaded with jQuery load(), because that mechanism works
asynchronously, and #sidenav was part of the DOM before it ran.
Once we started merging HTML fragments directly into the pages, the
script got called before #sidenav was defined, so the icon was
always being removed.
One solution would be to move the script to footer-incl.html, to
follow the preferred practice of placing scripts at the bottom of
the <body>. The better solution was to move the "no-sidenav" class
from #main to <body>, so that all components can see it. This lets
us use CSS rules to hide the icon.
This change applies the substitution scripts on the HTML files,
replacing away the jQuery load() calls with the actual file contents,
and setting the correct URLs to the prev/next buttons.
Fairly straightfoward in Python.
Also, fixed the sidenav references, which should be using the file
in the sgtutorial subdirectory.
Also, tweaked index.html a bit.
Added a SourceGen tutorial with lots of screen shots. Uses
"responsive web design" so it works well on mobile devices.
This version is using jQuery load() calls to pull in pieces, but
that causes a lot of blink when loading because the loads are
asynchronous and may not complete until after the initial page
render has finished.
Tutorial prev/next links not yet working.
