Updated lecture examples

irlc/lectures/lec04/lecture_04_harmonic.py

irlc/lectures/lec04/lecture_04_lunar.py

irlc/lectures/lec04/lecture_04_pendulum_random.py

irlc/lectures/lec04/lecture_04_pid_d.py

irlc/lectures/lec04/lecture_04_pid_iA.py

irlc/lectures/lec04/lecture_04_pid_iB.py

irlc/lectures/lec04/lecture_04_pid_p.py

irlc/tests/tests_week03.py

irlc/tests/tests_week04.py

irlc/tests/unitgrade_data/Exam5InventoryEvaluation.pkl

irlc/tests/unitgrade_data/Exam6Toy2d.pkl

irlc/tests/unitgrade_data/ExamQuestion7FlowersStore.pkl

irlc/tests/unitgrade_data/Problem1BobsFriend.pkl

irlc/tests/unitgrade_data/Problem1DiscreteKuromoto.pkl

irlc/tests/unitgrade_data/Problem1Kuramoto.pkl

irlc/tests/unitgrade_data/Problem2BobsPolicy.pkl

irlc/tests/unitgrade_data/Problem2DeterministicDP.pkl

irlc/tests/unitgrade_data/Problem2DeterministicInventory.pkl

.../unitgrade_data/Problem3InventoryInventoryEnvironment.pkl

irlc/tests/unitgrade_data/Problem3PID.pkl