[Piglit] HTML summary rewrite

[Dylan Baker]

This is a rather invasive patch set that starts to replace the summary
backend.

There are a couple of reasons for rewriting the backend rather than
making incremental changes. The first reason is that the old summary
backend is nearly uncommented, and nearly incomprehensable. The second
reason is philosophical, I didn't like that the generation was being
done partially in the piglit-summary-html.py and partially in summary.py,
It makes much more sense to do it in one place.

The design principle is that one creates a summary object, and then calls
a method on that object to generate output, whether they want text, HTML,
some kind of XML, or anything else really. Which makes the code simpler to
follow, since there is very little not being done in summary.py. This also
has the advantage of moving the majority of the code into compiled pyc
files and out of jited py files.

Patches 1 and 2 lay some ground work for the patch series, by reworking
a few things in the existing code

Patches 3 through 6 are the actual conversion from the old summary to the
new summary. The goal here it to produce HTML as close as possible to the
output of the previous implementation.

Patches 7 through 12 Introduce some enhancementments to the new code.
Mainly cleaning up the HTML output, or making some enhancements that
are different from the previous behavior