HQL Query Parsing via PEG Grammar #92

[vnayar]

This is a draft PR which is not yet complete, but due to the amount of work remaining, I thought it would be a good idea to share some of the early progress.

There is a new module added as hibernated.hql, and this module contains only the logic to parse HQL queries, which will serve as a the basis to support a much larger set of features than just FROM ... WHERE ... HQL queries. Furthermore, when properly integrated, PEG parsers can give users far more precise feedback in terms of syntax errors.

Running dub test currently prints out what a parsed query looks like, which can be used later for interpretation.

This work relates to the desire to add more HQL features, such as bulk insert/update/delete mentioned in Issue #92.