rename yellow -> syntax_node

why yellow in the first place? Its red + green.

crates/ra_syntax/src/validation/block.rs

@@ -1,6 +1,6 @@
 use crate::{SyntaxKind::*,
     ast::{self, AttrsOwner, AstNode},
-    yellow::{
+    syntax_node::{
         SyntaxError,
         SyntaxErrorKind::*,
     },

crates/ra_syntax/src/validation/byte.rs

@@ -5,7 +5,7 @@ use crate::{
     string_lexing::{self, StringComponentKind},
     TextRange,
     validation::char,
-    yellow::{
+    syntax_node::{
         SyntaxError,
         SyntaxErrorKind::*,
     },

crates/ra_syntax/src/validation/byte_string.rs

@@ -1,7 +1,7 @@
 use crate::{
     ast::{self, AstNode, AstToken},
     string_lexing::{self, StringComponentKind},
-    yellow::{
+    syntax_node::{
         SyntaxError,
         SyntaxErrorKind::*,
     },

crates/ra_syntax/src/validation/char.rs

@@ -8,7 +8,7 @@ use crate::{
     ast::{self, AstNode, AstToken},
     string_lexing::{self, StringComponentKind},
     TextRange,
-    yellow::{
+    syntax_node::{
         SyntaxError,
         SyntaxErrorKind::*,
     },

crates/ra_syntax/src/validation/string.rs

@@ -1,7 +1,7 @@
 use crate::{
     ast::{self, AstNode, AstToken},
     string_lexing,
-    yellow::{
+    syntax_node::{
         SyntaxError,
         SyntaxErrorKind::*,
     },