Move in_section to a util module.

src/parser/mod.rs

@@ -1,5 +1,6 @@
 mod bold;
 mod combinator;
+mod document;
 mod error;
 mod link;
 mod list;
@@ -7,7 +8,7 @@ mod paragraph;
 mod parser_context;
 mod parser_with_context;
 mod text;
-mod document;
 mod token;
+mod util;
 pub use document::document;
 type Context<'r, 's> = &'r parser_context::ContextTree<'r, 's>;