Begin removing of snipper dependency

.gitignore

setup.py

src/coursebox/core/__pycache__/info.cpython-38.pyc

src/coursebox/core/info.py

...al/__pycache__/homepage_lectures_exercises.cpython-38.pyc

...box/material/__pycache__/lecture_questions.cpython-38.pyc

src/coursebox/material/__pycache__/snipper.cpython-38.pyc

src/coursebox/material/snipper.py