adds multiple command buffers and bits of synchronization.
is not correct at all:
- no depth buffer barrier
- no ubo slots in render
- no proper render memory management
- no ray tracing support whatsoever
- ... etc
now vulkan can do screenshots too. however, it depends on blits being
available between swapchain and rgba8 formats, so if it's not the case
for some reason, the resulting image will have mixed components.
