[wgsl] rewrite with our own parser

Cargo.toml

@@ -13,9 +13,7 @@ license = "MPL-2.0"
 bitflags = "1"
 fxhash = "0.2"
 log = "0.4"
-pest = "2"
-pest_derive = "2"
-spirv_headers = "1"
+spirv = { package = "spirv_headers", version = "1" }
 
 [dev-dependencies]
 env_logger = "0.6"

src/lib.rs

@@ -1,7 +1,3 @@
-#[macro_use]
-extern crate pest_derive;
-extern crate spirv_headers as spirv;
-
 pub mod back;
 pub mod front;
 mod storage;