BUG: Fixed intermittent memory issue in terminologies

When loading a terminology context from segment descriptor, the Json array that holds recommended color of the last segment was sometimes deleted from memory, and parsing those values became undeterministic (invalid value or crash).
With the color array deep copied using the correct Json document object as allocator, the issue is fixed.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@25683 3bd1e089-480b-0410-8dfb-8563597acbee