Verify that v3.8 features require `#version 3.8`

[c-lipka]

Unless #version 3.8 is specified, any v3.8 features should either be disabled (if automatic) or trigger a warning (if requiring extra syntax), so that the user doesn't accidently mark a scene as v3.7 compatible that actually requires v3.8 to render as intended.

It needs to be verified that this is true for all v3.8 features.

It also should be douible-checked that the equivalent is true for all v3.7 features unless #version 3.7 or above is specified.