I was slowly getting cancer from having to write the unreadably awful
VK_FORMAT_R666G666B666A666_SRGB all the time. Besides that:
- All pixel formats are documented to show what's guaranteed for them
by the spec. Pretty useful I'd say.
- The old hasVkFormat() and vkFormat() converters operating on a
VkFormat are deprecated in favor of new hasPixelFormat() and
pixelFormat() that use the PixelFormat enum. Similarly as done in the
GL wrapper.
- All APIs that took a VkFormat before take a PixelFormat now, together
with having conveinience overloads for Magnum::PixelFormat and
Magnum::CompressedPixelFormat. Again similarly as done in the GL
wrapper, also the first step on being able to *directly* use data
imported with the Trade library with Vulkan.
This is what I needed BigEnumSet for -- good thing I didn't even try to
have 128-bit enums because I'm now at 110 values and it's still far from
complete. Next step is enabling those features when creating a device,
which should hopefully be a lot less code, reusing most of what was
here.