Follow cl-gfx 425267a: the types functions declare
Formats and Types lists the new types data-vector, data-element-type
and bind-group-index. The API reference and the pages on passes and
textures give the ranges of counts, indices, offsets, sizes, mip levels
and depths, and Errors and Validation shows how SBCL words a refused
argument, which replaces the message for an unknown element type.
