Brain interface changed

All behaviors are now targeted.

    me.brain.activate('seek', other)
    me.brain.is_in$U('seek', other)
    // => true

    me.brain.is_in$U('seek', mom)
    // => false
Gate singleton responders.

Imagine that you want a very particular behaviour
for every object of a type. Imagine, for example,
that you have Button:Gate and every button is
supposed to perform a particular action.

Then you can now type:

```javascript
var b = new Button("erase_id", null,
   {
      do_onmouseover: function (event, element){
         alert("I'm erasing your database! :p")
      }
   }
)
```