Use rpf namespace for rpf functions.
Use rpf namespace for rpf functions.

These were producing CRAN notes in Windows, even though they did not
seem to produce notes in Linux.

mhunter1/OpenMx,JuKa87/OpenMx,jpritikin/OpenMx,mhunter1/OpenMx,jpritikin/OpenMx,jpritikin/OpenMx,jpritikin/OpenMx,JuKa87/OpenMx,mhunter1/OpenMx,mhunter1/OpenMx,mhunter1/OpenMx,JuKa87/OpenMx,JuKa87/OpenMx,jpritikin/OpenMx,mhunter1/OpenMx,jpritikin/OpenMx,JuKa87/OpenMx,JuKa87/OpenMx