Merge pull request #506 from alancutter/boxShadowSupport

Add support for animating the box-shadow property
fixed
Merge pull request #508 from mikelawther/mychange

Fixed generation of start events for delayed animations
Renamed time drift to time lag to match updated spec
Added timeLag and _pausedState attributes
Added playing attribute
Added finish() method to Player
Added play() and pause() methods to Player (not working 100%)
Implemented reverse() method on player (not 100% working)
Fixed unpausing in reverse() method
Added temporary playground page for testing the new Player API
Switch speed up/down shortcuts to use the numberpad for cross browser compatibility
Added cancel() to Player
Added player seeking shortcut
Made logging togglable and added additional log targets
Updated playing attribute to match spec more closely (has weird dependency on paused state)
Added player.finish() shortcut
Added _pauseTimeLag logging
Added cancel() to Player
Added nullifiy pause time step to seek method