ember: Give per-frame progress updates when rendering animations

[lx45803]

I'd like to see an option (defaulting to on) to print a progress line after each frame is finished saving. For animations, overall progress is more important than the progress of any one frame. Furthermore, I'd imagine this would be effectively free from a performance standpoint, since it doesn't need to interact with the renderer at all.

[Matt Feemster]

If you supply the --verbose option on the command line, that shows you the image out of the total that you are rendering, such as 23 / 75

Tell me if this is sufficient.

[lx45803]

It spits out 8 lines for each frame rendered, which is more than I'd like, but it works well enough for my needs.