Autobind parameter for declaring components

Adds a special `autobind` role when creating components.  This is a shorthand for binding functions to events, with the added benefit that they'll be automatically unbound when the component is removed or destroyed.  You use it like this:

```
Crafty.c("MyComponent", {
	autobind: {
		EnterFrame: function(){
			// this function is bound to EnterFrame
		},
		Moved: function(){
			// this function is bound to the "Moved" event
		},
		// We can give a reference to a function instead!
		Change: "_changeFunction"
	},
	_changeFunction: function(){
	 	// This function is bound to "Change" by its name, but can still be called normally as a method on the component
	}
});

```

I'd probably want to go through and switch some of the built-in components to use this (as well as `remove()`) at some point.
Well, we still have to test that `comp` isn't undefined, buy I guess we don't need to test for autobind.