Add optional animation params to animatable property/attribute setters.
Make svg.Element.addAnimation_ protected (needed by subclasses). Remove "_".
remove attr name from <animate> and <set> ctors. It will be set via setter.
add optional animation params to <circle> setters.
add optional animation params to <ellipse> setters.
add optional animation params to <linearGradient> and <radialGradient> setters.
update <animation> tests to conform to f04972d6. (oops.)
add optional animation params to <line> setters.
add optional animation params to <path> constructor, setters, factory function.
add optional animation params to <rect> setters.
add optional animation params to <solidColor> setters.
add optional animation params to <stop> setters.
add optional animation params to <svg> setters.
add optional animation params to <text> setters.
add optional animation params to <textArea> setters.
add optional animation params to <use> setters.
add optional animation param to editable setter (<text> and <textArea>).