Initial commit
Added three scraps.

- Vertical centering with translate3d
- svg viewBox and preserveAspect magic
- clip-path experiment, broken in chrome
- flexbox
Added one working and two broken demos.

- css_filters
- dynamic_flexbox is broken. I’m trying to do way too much there.
- sidebar_gestures is broken. It seems like it should be much simpler,
alas.
- The metaindex file works tho.
Spiffier clip paths demo.
Added scrapbook demos.