Since depth/stencil images can't be linear, I needed buffer/image copies
to test those, and conversely to test buffer/image copies I needed image
clears.
A pretty big chunk of work, and it led to a discovery of a SwiftShader
bug, which I will work around next. First Vulkan driver workaround, so
the whole scaffolding needs to get added as well.
After I implemented the render pass wrapper, seeing how the
RenderPassCreateInfo structure and its dependencies were HUGE compared
to the actual tiny and lean RenderPass, I felt uneasy dragging their
definition along to every place where a RenderPass gets used. It's not
as bad with the others, but as new extensions are implemented I expect
that to get the same.
This change makes it easier for me to accept that Image.h / Buffer.h
depends on Memory.h. There isn't a real measurable difference when
building Magnum itself (50 ms out of 7 seconds for the Vk library
alone), but that's because most of the code (and tests) needs the
CreateInfo structures anyway.