Jifty::Mason::Halo - Class for drawing "halos" around page components
Whenever we start to render a component, check to see if we can draw a halo around the component.
Either way, record halo metadata.
When we're done rendering a component,
record how long it took and close off the halo span if we have one.
Returns true if we're not currently inside the "Body" section of the webpage OR the current component is a subcomponent. (Rendering halos for subcomponents being too "heavy")
Once we're just about to finish rendering our HTML page (just before the </body> tag,
we should call render_component_tree to output all the halo data and metadata.
