Add a short title/description into the filename of a notebook
holding exercises. In the past, students often did not find
the exercise files right away in class.
- add sample_package:
+ __init__.py => high-level description and imports
+ matrix.py => define a Matrix class
+ vector.py => define a Vector class
+ utils.py => package-wide utilities
- streamline the code snippets in the chapter 11 notebooks
to align with the sample_package
