Refactoring all bunch of code and fixed error with END token

[Roshiago]

Hi @davidcallanan, i watch your video series about writing VERY OWN programming language and i have an idea. Keeping this is one single file for me is not ok, and then i realized that i can rewrite code to separated files and fix some bugs in your code base. For example: i fix issue with END/EOF token while parsing for or if statement in while loop (in ep14 folder: parser.py, 593 to 608 lines) Programm raise an exception while parsing this statements and work correctly for some reason.