HPCC-11201 Add "getTreeWithProperties" to GraphControl

Fixed compiler cast warnings (double to int).

Signed-off-by: Gordon Smith <gordon.smith@lexisnexis.com>
Merge pull request #161 from GordonSmith/HPCC-11201

HPCC-11201 Add "getTreeWithProperties" to GraphControl

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>