Added support for css pseudo classes
:first-child, :last-child, :nth-child, :nth-last-child, 
:first-of-type, :last-of-type, :nth-of-type, :nth-last-of-type,
:only-child, :only-of-type, :empty,
:root
Merge commit 'db2d5aa85352fe63531540ef396b944e2fe58e2c'

Added selector javadoc