I've done it! You can now define shader functions outside of a pipeline
and they will be mixed into the shader just prior to varjo compilation.
This is a HUGE win as far as organising code goes and I am very happy to
have reached this stage. I still need to confirm that this works with
externally defined shader stages aswell but this will be a small job.
Phew! Rock on, I guess I need to make some videos soon