Create structure for export snippets.

src/parser/mod.rs

@@ -9,6 +9,7 @@ mod element;
 mod element_parser;
 mod entity;
 mod exiting;
+mod export_snippet;
 mod fixed_width_area;
 mod footnote_definition;
 mod greater_block;
@@ -73,6 +74,7 @@ pub use object::AngleLink;
 pub use object::Bold;
 pub use object::Code;
 pub use object::Entity;
+pub use object::ExportSnippet;
 pub use object::Italic;
 pub use object::LatexFragment;
 pub use object::Object;