Modify .gitignore
XML lexer now properly deals with errors; Removed EndOfFile token

- Removed EndOfFile token, it will be dealt with parser by
  emitting None;
- Fixed errors caused by EndOfFile token, and added proper error
  implementation;
Removed unused functions

- Removed `escape` and `unescape` fn as they weren't used.
- Removed unnecessary imports required by said functions
Modified way Mark works

- Added offset message and changed way Mark works