Dynamically create frag shaders for clearning attachments and images.
Dynamically create frag shaders for blitting scaled images.
MVKGraphicsPipeline don't create MTLRenderPipelineState if vertex function conversion fails.
MVKComputePipeline don't create MTLComputePipelineState if compute function conversion fails.
Handle SPIRV-Cross errors thrown during SPIR-V parsing in compiler construction.
Set undefined property limits to large, but not max, values to avoid casting issues in app.
Mark multiDrawIndirect features as available.
Update to latest SPIRV-Cross version.
Update to MoltenVK version 1.0.5.
fetchDependencies script now in top directory to avoid Travis caching of
External directory. fetchDependencies is now smart about fetching vs cloning
and building only what is necessary.
