Refactor entities in level_002 to move rendering to the renderer

[sfoster]

With the new renderer, the level needs to implement a getRenderList method to return all the things (entities, particles, whatever) that need rendering, in the order they should be rendered.

The example method has a trivial example implementation. The level's render method will be called, again, in the example level you'll see it passes the return value of this.getRenderList() to rendererer.render( ).

The renderer currently only supports sprite-based rendering (ctx.drawImage).So this task is blocked by another which is to implement the box/line fills currently used for walls, doors, etc.