v0.8.8.  `step` function no longer binds `this` keyword.

Old style:

  tweenable.tween({
    from: {x: 0},
    to: {x: 10},
    step: function () {
      console.log(this.x);
    }
  });

New style:

  tweenable.tween({
    from: {x: 0},
    to: {x: 10},
    step: function (state) {
      console.log(state.x);
    }
  });
Big overall cleanup.  Removes Tweenable#to and shorthand tweening API.

Tweenable#tween now only accepts a configuration object.

Squashed commit of the following:

commit 560360fc078bcac8a279004e62f5ab15b2e8b19c
Author: Jeremy Kahn <jeremyckahn@gmail.com>
Date:   Sun Aug 25 18:08:46 2013 -0700

    Big code and doc cleanup.  Updates grunt-dox to 5.0.

commit b2f5d1bc88f95cef2e5afd448b4397615861bff3
Author: Jeremy Kahn <jeremyckahn@gmail.com>
Date:   Sun Aug 25 17:27:17 2013 -0700

    Updates package files and index.hmtl.  Rebuilds binaries.

commit 463b021df4123902afe0ba948952ae795afcb934
Author: Jeremy Kahn <jeremyckahn@gmail.com>
Date:   Sun Aug 25 17:01:29 2013 -0700

    Removes Tweenable#to.

commit ecc3e3d4b1e5314e103bad9f797c4566dd0ee3af
Author: Jeremy Kahn <jeremyckahn@gmail.com>
Date:   Sun Aug 25 12:26:05 2013 -0700

    Removes non-config object method of calling Tweenable#tween.