3 changes:
1. Properly initializing vtkCPProcessor.
   vtkCPProcessor needed to be initialized before adding in a
   vtkCPPythonScriptPipeline.
2. Exporting API methods so that they can be used by other libraries/executables.
   For GCC and Windows, the export macros weren't being used so that other
   libraries and executables that tried to link to methods in this library
   would cause problems.
3. Change multiblock data set iterator calls to match with changes to VTK.

Change-Id: I2ff2a7cb038989a8a42efc545f93b81dc7a69710