delete files from add-numpy-reference branch

book/programming/code/numpy_0.ipynb

book/programming/code/numpy_1.ipynb

book/programming/code/numpy_2.ipynb

book/programming/code/numpy_3.ipynb

book/programming/code/numpy_files/arr.npy

book/programming/code/numpy_files/barcharts.png

book/programming/code/numpy_files/example_data.csv

book/programming/code/numpy_files/example_data.txt

book/programming/code/numpy_files/plotting_functions.py

book/programming/code/numpy_files/taxi_duration.txt

book/programming/python_topics/classes_solution.ipynb

book/programming/python_topics/modules_solution.ipynb