Refactor Demo

[bigtimebuddy]

Replaces #81

This uses Rollup to build the demo project in tools/demo.

[finscn]

I can't wait it.

[finscn]

Please don't resize bg sprite when window resize.
If do that users will can't know If "the bg resize effect" is filter's effect.
We could give it a big size(big enough) like this :

    bg.width = window.screen.availWidth;
    bg.height = window.screen.availHeight;

[bigtimebuddy]

I’m not sure I agree with your concern about the background sprite. What about a proportional scale? So it maintains the same aspect ratio?

[finscn]

The proportional scale is better than current setting.
But if only scale bg and don't scale the fishes , it'll puzzle somebody still, e.g. Me.