New Animation Style: Unroll

[crmorford]

Instead of Plots growing up from the x-axis, have them unroll horizontally.

[crmorford]

Testing Notes:

• Animation happens at a reasonable speed (not too slow, not too fast)
• Animation works on all Plot types (hbar, vbar, scatter, line, area)
• Animation works with x-axis as time/category/numeric
• Animation works with y-axis as category/numeric
• Animation works when multiple plots are merged and animated
• Animation works when multiple plots are merged but only one is animated
• Unroll Animation can be used on one plot, and grow-from-bottom on another plot, when merged together

Edit due to Justin's comment below:

• Animation works on Line and Area
• Applying unroll animation has non-breaking behavior on Bar and Scatter

[jtlan]

@crmorford I think this ticket only applies to Line and Area. Plots with a node for each data point can already get a similar effect by use of iterative delays.