Ignore xml_node executable
Simplified structure of Attribute declaration
Completed Notation and Enumeration part of attribute types
Modified .gitignore for new extensions
Fix changes in new Rust

#link is no longer used, now we use crate_id for packaging crates
Changed ~ into & pointers

No reason to use owned pointers, when we can use borrowed
Changed error handling in lexer

Changed the number of arguments the `handle_error` functiont takes
Add context variable to Lexer for pretty errors