assembler: Tokeniser updates, Compiler Engine is back finally

assembler/src/source/token.rs

@@ -31,6 +31,8 @@ pub enum TokenType {
     Newline,
     /// End of file.
     Eof,
+    /// A line comment. This is to be filtered out of the token stream.
+    Comment,
 }
 
 #[derive(Debug)]