* Add NgramCharModel to text.py

* Update text.py

* Update

* Fix NgramTextModel bug

* Add new tests for NgramTextModel

* Bug fixing

* Spacing

* Update test_agents.py

pep8 changes, showed flake8 errors

* Update test_agents.py

* Update test_agents.py

* Update test_agents.py

* Update test_text.py

added missing whitespace after comma

* Update utils.py

added space after comma

* Update search.py

added space after comma

* Update probability.py

added space after comma

* Update learning.py

added space after comma

* Update planning.py

added double_tennis_problem

* Update rl.py

In the pseudocode figure 21.8, the first 'if' starts with argument 's', which is the previous state, not s1(i.e, the current state).

* Update search.py

the 'uniform_cost_search' in notebook 'search-4e.ipynb' resembles more to the pseudocode in book.

* Update search.py

* Update search.py

* Update search.py

Add DecisionTreeLearner, NeuralNetLearner and PerceptronLearner tests

* move play_game into games class

* display current state before prompting for action

* fixed player swap bug

* display available moves to human players

* make tests pass

* updated games.ipynb with refactored games.py

* fixed typos in games.ipynb

* Add Perceptron Section

* Add Perceptron Image

* Added testcase for agents.py

* spacing around commas was wrong

created a parameter size in the function leave_one_out(learner, dataset, size=None):

minor error fixes.

* added documentation, standardised docstring quotes

* made search.py pep8 compatible using flake8

* fixed bug in OnlineDFSAgent

Add test for the following functions from csp.py

* revise
* AC3
* first_unassigned_variable
* num_legal_values
* mrv

* Update learning.py

* Added remove_examples function

Make load_MNIST function easier to read

In learning.py, I added the Hamming Distance metric.

* Rearranged Tests

- test_ngram_models to the top
- added test_viterbi-segmentation
- removed test_unigram_text_model

* "test_ngram_models" to "test_text_models"

* Improved BlindDog example

* Added 2D GUI IPython capability

* Demonstrated 2D Environment with GUI

* allowing import without ipythonblocks installed

* added tests for Direction

* fixed Direction arithmetic error

* Delete fig_5_2.svg

* add fig_5_2.png

* Update games.ipynb

* Update text.ipynb

* Update text.ipynb

* Update some comments

* Cleanup and remove some duplicate initialization

* Fix some comments quotation and little bugs: raising Exception instead of raising Failure, random.randrange(a,b) instead of random(a, b)

* Fix some comments quotation and remove explicit inheritance from object

* Fix 'r' in front of the ```parse_csv``` comments

* Fix quotation in comments

* Fix quotation in comments and fix bug in 'KB_AgentProgram'

* Update agents.py

* Update test_grid.py

* Update grid.py

* Update utils.py

in pseudo code the sequence of arguments is " WEIGHTED-SAMPLE-WITH-REPLACEMENT(N, S, W)"  same must follow in function "particle_filtering" in the file probability.py

* Update learning.py

weight_sample_with_replacement sequence of args

* Update probability.py

 weighted_sample_with_replacement sequence of args

* Update search.py

* Added Plurality Learner Plot Image

* Update learning.ipynb