* Changed front::glsl::error::ErrorKind::Semantic to use Cow

* cargo fmt

* appeasing clippy

* Update src/front/glsl/functions.rs

Co-authored-by: monocodus[bot] <49363530+monocodus[bot]@users.noreply.github.com>

* Fixed more clippy errors

Co-authored-by: Dzmitry Malyshau <kvark@fastmail.com>
Co-authored-by: monocodus[bot] <49363530+monocodus[bot]@users.noreply.github.com>

- Update parser to match the latest spec: https://github.com/gpuweb/gpuweb/pull/1326

Related to #330

* [glsl-in] Cast gl_VertexIndex to SInt

* [glsl-in] Use conversion cast (gl_VertexIndex)

- Also cast gl_InstanceIndex

* [glsl-in] Simplify global var lookup

* [glsl-in] Fix missing comma