GeezerVison

Add an interactive JS visualisation to demonstrate how the sampling
profiler works. A small demo program is shown executing line by line,
demonstrating how stack frames are created and destroyed and how samples
are taken periodically during the process.

A new Sphinx extension is used to capture and inject the trace into the
JS file during documentation build to make these traces reproducible
(and avoid hard coding them in the source code).

Include the JS and CSS files in the Sphinx extension to make sure Sphinx
properly includes these when producing all output types.

Moved function colors to a lookup map and easing definitions to a module
constant so they aren't recreated on each call. Cached the background
element reference in DOMStackFrame instead of querying it on every
hover. Chained the regex replacements in syntax highlighting into one
expression.

Removed the CSS color rules for specific functions since colors are now
set in JS, along with a duplicate color variable and two methods that
were never called.