reactivate scene after context lost

[profelis]

usage:

    function onDisposed()
    {
        engine.onReady = function () {
            engine.free(); // dispose debug line and point
            scene.free();  // dispose all buffers and shaders           
            tm.rebuildTextures(); // tm:TileManager
        }
        engine.init(); // reinit
    }

demo: https://dl.dropbox.com/u/1036911/h3d/contextLost/index.html

src: http://pastie.org/private/3ahbvmveacdpi6ctefakyw

[ncannasse]

I made several changes recently in order to support lost of context:

• you can setup a onContextLost callback on textures in order to upload them again
• primitives should be reallocating themselves (use buffer == null || buffer.isDisposed() if you have custom ones)
• you will get an engine.onContextLost callback that you can use to rebuild dynamic buffers
  Tell me if you want to suggest further changes