Added tests for insertBefore event firing

And cleaned up documentation a tiny bit
Added "type" field to DOMEditAction

Somehow this was forgotten the first time around (!).
Updated tests correspondingly.
Fix: formatting error in a link in the docs

Can't start a markdown line with #, or it makes it a heading.
Added ToC support to generated HTML doc pages
Completed tests for emission of normalize events
Bug fix in doc page ToC generation
Improving appearance of generated doc pages
Fixed outdated documentation from earlier edits
Added a method for clearing DOMEditTracker stack
Bug fix: both Node and Element prototypes must be modified
Tiny documentation tweak
Bug fix: Earlier tests were failing due to removeAttribute

Now that removeAttribute functions correctly, sending events to
DOMEditTracker, all the id manipulation done by the tracker was
generating extra events.  So we now clear them out before testing.
Added test for removeAttribute event emission
Added test for removeAttributeNode event emission
Added test for removeChild even emission
Bug fix: DOMEditAction: replaceChild had wrong arg order

I can pick any order I want, of course, but I want it to match the
order of Element.replaceChild(), for convenience.
Added test for replaceChild event emission
Added test & bug fix for setAttribute event emission
Added test for setAttributeNode event emission