Rework Sensor/Film/Output relationship

[PearCoding]

Allow advanced sensors despite standard cameras and many other features:

Sensor

• [ ] Batched ray generation
• [ ] Batched incident radiance handling
• [ ] Various sampler handling
• [ ] (Multiple sensors by handling one after another)

Film

• [ ] Optional filter handling per (supported) channel -> Requires thread safe tiled approach
• [ ] Monotonic or other kind of mappers based on incoming spectral wavelength
• [x] Pushforward custom AOVs (with LPEs) from integrators or other parts of the raytracer

Output

• [x] Custom output devices (e.g. image, network, Jupyter, IPC etc)

Problems

• [ ] The project files have to handle this accordingly. Multiple sensors would be good, but one is used at a time anyway. This is only useful for multiple goniometer like sensors, but could also be handled by an python script generating project files...
• [x] Proper interface for possible adaptive or progressive sampling
• [ ] Plugin writers do not have to bother with sampling and film mapping if not desired. A new lens based camera plugin should not enforce multiple copied lines of code.

The general dependency is: Sensor > Film > Output but initialization requires at least the mutual communication of sensor and film

A good starting point is the PBRT sensor/film relationship