Show preferred vector widths with --list=opencl-devices. How the heck did
I miss this until now!? It's important information and we can use the same
call to default to vectorization - or not - at runtime for some formats.
Merge branch 'bleeding-jumbo' into bleeding-mask

* bleeding-jumbo:
  Show preferred vector widths with --list=opencl-devices. How the heck did I miss this until now!? It's important information and we can use the same call to default to vectorization - or not - at runtime for some formats.