improve error messages for bad comparison.
Allow comparison of different types in sort.
Fix bug in JOIN implementation (still incomplete and buggy)
Some more work on JOINs (still buggy and incomplete)
Some progress on getting joins working.
Remove some cruft
Improve efficiency of joins.
Joins semi-working.
Some work on adding inequality test operators.
Move a large portion of the join code into the runtime.
More work on JOINS