simplified the export shutdown behavior

- the delegate is no longer responsible
- the ‘finshing’ status phase is no longer necessary
- was able to ditch the _meta.running flag
disconflated pagination and pattern-based names

- self.paginated flags a multipage pdf export
- self.filePath may well be defined in non-pdf cases (e.g. if there’s a
single output file being written)
even less special-casing in export-handling

- the vm now hands things off to an export-session even when only a
single frame is being rendered
simplified event handlers in export delegates
experimenting with color calibration

- r/g/b and greyscale seem reasonable
- i’m less convinced this is the right way to handle h/s/b and c/m/y/k