Hive Grammar Parser Visualization

[David Mollitor]

Hello Gang,

https://issues.apache.org/jira/browse/HIVE-23171

I just wanted to share with you a tool that I put into the master branch of
Hive.  It is a small command-line tool for building visualizations of the
output of the Hive ANTLR parser.

I hope you find it useful.

Thanks.