Port some DFXML code to RegXML
Add CellObject elements
Fill in more RegXML logic
Fix some issues raised by unit tests
Use generic python3 executable
Fix path reference; enforce test erroring out
Use minor version
Implement and test HiveObject diffing
Add expected-values enumeration for value data type, and unit tests
Document changes and update versions

Signed-off-by: Alex Nelson <a.nelson@prometheuscomputing.com>