animateTransform rotate now supports cx xy

rotate transforms now support 'angle cx cy' as well as 'angle'.

http://www.w3.org/TR/SVG/animate.html#AnimateTransformElementTypeAttribute
  For a type="rotate", each value is expressed as <rotate-angle> [<cx> <cy>]
s/hasOptionalValue/numOptionalValues/.
This should be a for loop.