Solved more memory leaks

bob/learn/em/empca_trainer.cpp

bob/learn/em/isv_base.cpp

bob/learn/em/isv_machine.cpp

bob/learn/em/isv_trainer.cpp

bob/learn/em/jfa_base.cpp

bob/learn/em/jfa_machine.cpp

bob/learn/em/jfa_trainer.cpp

bob/learn/em/kmeans_trainer.cpp

bob/learn/em/plda_machine.cpp

bob/learn/em/test/test_plda.py