Improve animation support

[mwestphal]

• Add a CLI option to generate an animated camera orbit #1743
• Animation freeze when interacting with mouse #25
• Support saving multiple file when using --animation-autoplay and --output #46
• Add support for showing more than one animation in vtkF3DAssimpImporter
• Add support for selecting specific animaitons in vtkF3DGenericImporter instead of adding them all together
• Improve the option to be able to pass a list instead of relying on -1 to select them all

[mwestphal]

related to #902