Stunner - Case Modeler universal palette integration

This subtask represents one of several reasonable unit of work towards completion of BAPL-314. See parent issue for further details & other subtasks.

Palette Integration

• Bring in universal (shared) palette code (effectively replaces current palette)
• Change palette available items to match Case Modeler reqs
  • Human Tasks, Subprocesses, Subcases
• Change palette colors/icons
• keyboard shortcuts?