ViennaCL: Updated code for new interface to PetscObjectComposeFunction() and XXXRegister()
ViennaCL: Eliminated whitespace violations, removed/fixed erroneous comments.
ViennaCL: Eliminated dead/unused code
ViennaCL: Added MPI-implementation for AIJ matrices.Follows the existing interface for CUSP and CUSPARSE.Compiles and passes standard 'make test'. No additional testing performed yet.
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