1.7

• Adds support for add-to-item for deltas and snapshots (the Discovery Engine
  does not support add-to-item for bulk or full changesets). The add-to-item
  configuration element supports the same attributes and child configuration
  elements as set-item.
• Adds another subquery test scenario.
• Fixes Data Tool Outputs Empty Strings: If a column returns an empty string,
  the data tool still outputs the column value. Empty strings should not be
  output.
• Fixes merge-columns should not be case sensitive.