Countup Animation

[shwaydogg]

• Add a api lifeline field to turn on the animation that will indicated the number of seconds to count up from the initial value to the final or normally displayed value for the lifeline.

• When switching to the lifeline or turning on the clock to the lifeline the number should start with the "initial value" and then count up to the final value over the given number of seconds.

[adrian-the-git]

We have "static linear growth" lifelines where the rate of change is zero. Do these need to be supported?