Add ability to have a generic "behavior" function that gets notified via the parser

[david]

Something like so:

function sayHi(node, parsedNode) {
  node.onclick = function() {
    alert("Hello " + node.getAttribute("username") + "!");
  }
}

parser.addBehavior(function(node) {
  return node.hasAttibute("username");
}, sayHi);

[Dustin Machi]

Alex already committed something along these lines a few weeks ago.

[(none)]

Milestone 0.3release deleted