Move the function coo2csr to 'common.h' as a template function.
Rename MC64 classes

MC64  -->  MC64_base (this is the base class)
OldMC64 --> MC64 (using "standard" CUDA, i.e., no unified memory)
NewMC64 --> MC64_UM (using unified memory; requires CUDA >= 6.0)
Update driver programs.