Rollback to one folder

Remove test_vector_clip() in utils_test.py

Fixed small error in csp.py where grid was spelt gri

Implemented and_or_graph_search

Fix relative imports

- Fix relative imports in base of is a package or not
- Fix not working notebooks
- Add notebooks to packages sources

Ipython created notebooks with python3 kernels

Changes in util.py

Add test grid

Add test cases for histogram in utils_test.py

cleaned 2-d grid methods in utils.py as we got them in grid.py

empty __init__.py in tests/ so build passes in local repo

Finished porting to Python 3