Expression interpreted evaluation. Auto generate interpreter for Drill simple function. Work in progress.

wip

more WIP for interpreter.

More work in progress.

more work in progress.

code clean up.

More Work In Progress.

Work in progress. support DrillBuf as workspace var.

More work.

More work.

work in progress.

reverse change in project record batch.

Expression interpreter. Works for nullable input now.

More work in progress.

work in progress.

code clean.