A copy of code in "The Definitive ANTLR 4 Reference" for ANTLR 4.6

The Definitive ANTLR 4 Reference was published 4 years ago. Many changes have happend from then on and code in the book may be corrupted. Some issues are fixed in this repo. All code here are compatible with ANTLR 4.6.

Fixed code in this repo are placed in same structure with the original code repo (https://media.pragprog.com/titles/tpantlr2/code/)