Add back support for named behaviors

[balderdash]

Behavior equality broke for old behaviors, because they were often written to create a new function every time you try to add or remove them, e.g.:

function float(sprite) {
  var behavior = function(sprite) {
    sprite.moveUp();
  }
  behavior.name = 'float';
  return behavior;
}

It used to work because equality was just based on the name, but now we can compare functions directly. Because equality is broken, you can add the same behavior multiple times and you can never remove a behavior.

(Some old behaviors still work because they declared the function once and just returned it over and over, but most weren't written that way).

This PR brings back name-based comparisons.

I tried writing tests, but the name property on functions is readonly outside of JSInterpreter, so I just had to verify manually. That behavior broke a couple tests as well.

[Hamms]

LGTM!