Merge pull request #129 from sorvell/master

Add support for dynamically loading polyfill (after document has loaded).
Remove Player.cancel()

See https://github.com/web-animations/web-animations-js/issues/136
Remove superfluous and unimplemented TimedItem.seek()
Remove superfluous TimedItem.reverse()

This functionality will probably be moved to Player.reverse(). See
https://github.com/web-animations/web-animations-js/issues/137
Fix AnimationGroup.clear()

Also remove superfluous TimedItem.clear()
Merge pull request #138 from steveblock/specUpdates

A few bug fixes and updates from the last meeting
Detect which calc function and transform property should be used
Merge pull request #140 from dstockwell/feature-detection

Detect which calc function and transform property should be used
Added support for feature-detected transform output. Modified test cases involving transforms to ensure they are compatible with Mozilla as well as WebKit.
Update README.md

include information about prefix handling and experimental features
Merge pull request #142 from shans/transform-output

Added support for feature-detected transform output. Modified test cases...