Rename source code files from .c to .cpp and from .h to .hpp

genmod/hh.cpp

genmod/hh_3DSchach.cpp

genmod/hh_toy_ac_start.cpp

genmod/hh_toy_ac_true.cpp

genmod/hh_toy_start.cpp

genmod/hh_toy_true.cpp

genmod/rheinstetten_elastic.cpp

src/CPML_coeff.cpp

src/CPML_ini_elastic.cpp

src/absorb.cpp

src/av_mat.cpp

src/calc_res.cpp

src/catseis.cpp

src/check_recfile.cpp

src/check_recpos.cpp

src/check_srpos.cpp

src/check_srpos.hpp

src/checkfd_ssg.cpp

src/comm_ini.cpp

src/comm_ini_s.cpp