removes the CSS blurs that were slowing down scrolling over the interlude.
adds SVG blurs to the interactive, in lieu of the CSS blur, and enables them to be toggled on and off.
doubles the throttling on scroll.
Merge pull request #22 from Etc-Gallery/increase-scroll-performance

Increase scroll performance by swapping out CSS blurs with SVG blurs and doubling scroll throttling. This closes #18