Clean up Python CoProcessing script logic.

This cleans up the logic in Python CoProcessing scripts and the export wizard.
Creating new Python modules (coprocessing, cpstate and cpexport) that are now
used instead of embedded codes. CoProcessing Python code has been revised to not
heavily rely on global variables and secret code stubs.

Change-Id: Ie36913fc2337ca4897d022d07c80f7912428d594
Removed vtkCPPythonProcessor.

Removed vtkCPPythonProcessor. Now, vtkCPPythonScriptPipeline initializes Python
when the first pipeline object is created.

Change-Id: I3349cc0e6aec3c763e0a351b419435f42be35aac
Merge topic 'clean_coprocessing_python' into next

27fb1e5 Removed vtkCPPythonProcessor.
aae473a Clean up Python CoProcessing script logic.