Open Topics for oryol-shdc

[floooh]

• find out how matching locations for vs-out/fs-in parameters are done in spirv-cross, right now it looks like it magically works, but this may be by accident, may need to manually enforce locations (e.g. by assigning locations in spirv-cross manually by alphabetical order).

• once the vs-out/fs-in locations are enforced, enable the validation for this in Shader.py again

• enable a way to include/exclude code by target shader language, preferably with standard #ifdef, but this may not be doable since it may affect the shader reflection information (if shader inputs/outputs are conditionally removed/alterered), so this may not be an option.