Current test methods:
testPacman_initial() - tests Pacman initialization
testGhost_initial() - tests Ghost initialization
testRestart() - tests that game is reinitialized in terms of PacmanActor
testPacman_node() - tests that PacmanActor can change GridNode positions
testGhost_node() - tests that GhostActor can change GridNode positions
testPacman_death() - tests that PacmanActor is killed according to GridNode
testPelletEating() - tests Gameboard+PacmanActor knowledge of pellets eaten
testGetPacman() - tests correct usage of Gameboard PacmanActors
testScore() - tests that score is incremented correctly
testLives() - tests that lives are decremented when necesary