Outer queries (subqueries) and lateral views explodes of lateral view explodes

This release adds the ability to run another query within a query. This is equivalent to running a subquery in SQL. The only current restriction is that the outer query cannot have a Window.

Lateral View's can now operate on a list of TableFunctors. This lets the LATERAL VIEW EXPLODE operation be applied to the result of another LATERAL VIEW EXPLODE field.