Add convenience functions for common animation workflows

[GenevieveBuckley]

It's been suggested a few times that it would be nice to have some pre-baked animations for common situations. This comment summarizes the idea well:

... making some standard "pre-recorded" "Movie" instances that you could then apply regardless of your data if you wanted to automate and standardize movie making - like a "zoom in" / "zoom out", or "loop through sliders once", or "full 3D rotation".

Pre-baked workflows

• 360 degree rotation of a 3D volume (may need to specify which axis is rotated?)
• loop through sliders (may need to specify which axis is looped through?)
• zoom in / zoom out (imo this one seems simple enough that the existing tools might be sufficient on their own)

Implementation

• [ ] Example scripts demonstrating these common situations (easy)
• [ ] GUI button to insert the pre-baked workflows into a longer movies. Being able to mix and match these building blocks with other keyframes set interactively would be very useful (could be difficult to implement)

[GenevieveBuckley]

I personally have also found that it is difficult to make a perfectly even 360 degree rotation animation with interactive keyframes.

Being able to mix and match these sorts of pre-set elements when making animations interactively would be very helpful.

[alisterburt]

Very cool! Won't implement myself but happy to provide guidance for anyone who wants to have a go :-)