Create structure for timestamps.

src/parser/mod.rs

@@ -47,6 +47,7 @@ mod subscript_and_superscript;
 mod table;
 mod target;
 mod text_markup;
+mod timestamp;
 mod token;
 mod util;
 pub use document::document;
@@ -104,6 +105,7 @@ pub use object::StrikeThrough;
 pub use object::Subscript;
 pub use object::Superscript;
 pub use object::Target;
+pub use object::Timestamp;
 pub use object::Underline;
 pub use object::Verbatim;
 pub use source::Source;