Consistent plt use

exercises/02450Toolbox_Python/Scripts/ex10_1_1.py

exercises/02450Toolbox_Python/Scripts/ex10_1_3.py

exercises/02450Toolbox_Python/Scripts/ex10_1_5.py

exercises/02450Toolbox_Python/Scripts/ex10_2_1.py

exercises/02450Toolbox_Python/Scripts/ex11_1_1.py

exercises/02450Toolbox_Python/Scripts/ex11_1_5.py

exercises/02450Toolbox_Python/Scripts/ex11_2_1.py

exercises/02450Toolbox_Python/Scripts/ex11_2_2.py

exercises/02450Toolbox_Python/Scripts/ex11_2_3.py

exercises/02450Toolbox_Python/Scripts/ex11_3_1.py

exercises/02450Toolbox_Python/Scripts/ex11_3_2.py

exercises/02450Toolbox_Python/Scripts/ex11_4_1.py

exercises/02450Toolbox_Python/Scripts/ex1_5_1.py

exercises/02450Toolbox_Python/Scripts/ex4_1_1.py

exercises/02450Toolbox_Python/Scripts/ex4_1_2.py

exercises/02450Toolbox_Python/Scripts/ex4_1_3.py

exercises/02450Toolbox_Python/Scripts/ex4_1_5.py

exercises/02450Toolbox_Python/Scripts/ex4_1_6.py

exercises/02450Toolbox_Python/Scripts/ex4_1_7.py

exercises/02450Toolbox_Python/Scripts/ex5_1_2.py