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>]
Configurable optional parameters and delimiter

transformRE now allows any number of optional parameters, and accepts a
'commaDelimited' bool to indicate if the parameters should be delimited
by a comma or spaces.
Merge pull request #39 from ewilligers/rotate-cx-cy

animateTransform rotate now supports cx xy