hikaru/gpu: clean up comments.
hikaru/renderer: add a visual aid to debug normals.

Press 'n' to toggle it.
vk/{main,games}: do not abuse VK_LOG for messages to the user.

So that we can optionally turn of VK_LOG when in non-debug (release?) builds.
vk/core: make VK_LOG and VK_ASSERT obey to NDEBUG.
hikaru/gpu: implement normals for static meshes.

I'm still not 100% certain about the encoding, but this change improves normals
in AIRTRIX, BRAVEFF and SGNASCAR a *lot*.