raster image of animate-elem-12-t

Test possible values for 'calcMode="spline"'

Two animations have been defined. For each animation, ruler lines and text are provided to help show what the correct behavior is. The black text and ruler lines help show the sizes and movement of the rectangles over time.

For calcMode='spline' in this test case, the initial rate of change is defined to be the same as linear, but the last jump has an ease-in/ease-out effect where the change is slower at the start and end but faster in the middle.