Multiview generator

[MartijnBraam]

Adds a new multiview section to the config to generate one or more multiview scenes. For every multiview an image source is also generated with an overlay with source labels.

• Merge after the dynamic scenes MR, this is build on top of it
• Could have warps added in so the transition to a multiview isn't super weird
• Need a way to have an imageSource initialized with an in-memory image (Support creating imagesource instances without a file #50)
• the sink source isn't implemented, depends on recursive scenes