Improve animation performance

[bryanbraun]

One quick way for us to improve the performance of these animations is to rely more on transforms, as explained in this article (and the following image):

The biggest opportunities are in areas where we could animate transform: translate instead of top/bottom/left/right. We can fix this in the following screensavers:

• [ ] Flying Toasters
• [ ] Bouncing Ball
• [ ] Fish
• [ ] Logo
• [ ] Messages
• [ ] Messages 2
• [ ] Spotlight

Other opportunities include:

• [ ] Hard Rain (currently animates width and height).
• [ ] Rainstorm (animates background color, which could be done with opacity)