Follow cl-vk 9af03d9: the global commands in a saved image
Concepts and the raw layer's page say that the global table holds the
loader's pointers of one process, which cl-vk forgets when a saved image
starts and loads again on its next use.
Describe cl-vk's conditions for misuse and its escape hatches
Misuse is a type-error where check-type can say what is wrong, and a
vk-error with a message otherwise; the struct macros' expansion-time
errors are vk-errors too. instance-commands, device-commands and
swapchain-images are escape hatches that refuse destroyed objects, and
swapchain-images has an entry of its own. device-queue takes :family
and :index. with-structs takes a foreign pointer for a field that
points to untyped memory. The generator no longer has *platforms*.
Add the reference pages and the sidebar; document enum keyword rules
Add API Reference, Errors, Lifetimes and Threads, Raw FFI Layer,
Generator and Registry, and Platforms and Testing. State the full rules
for enum keywords, including the prefix word kept before a digit
(:type-2d), and use :type-2d in the image view recipe.
