* Added python code for psource (#613)

* added psource code with optional highlighting (#613)

* Update notebook.py

* Update nlp.ipynb

* line ran too long; shortening

* Update nlp.py

* add chart parsing test

* add chart parsing section

* add cnf_rules to grammar

* Update nlp.ipynb

* Update test_nlp.py

* add more to CNF section

* add tests column

* add finished tests

* Update nlp.py

* add CYK parsing test

* add prob-grammar to notebook

* Update nlp.py

* add weighted choice

* tests for prob grammar + generation

* add test for weighted choice

* Update nlp.py

* Update knowledge.ipynb

* Update test_knowledge.py

* add version-space learner + small fix

* add test for version-space learner + trivial example

* Update README.md

* fix small bug in knowledge.py

If hypotheses was empty, it would fail.

* add knowledge.ipynb

* fix dollar signs

* add image

* Update text.ipynb

* fixing dollar signs

* Update nlp.py

* Update test_nlp.py

* Add files via upload

* Update nlp.ipynb

* add generate_random

* Update README.md

* add powerset to utils

* add powerset test

* Create knowledge.py

* Create test_knowledge.py

* add header docstring to knowledge.py

* update learning docstring

* minor edits in knowledge.py

* Fixed truncated_svd

* Moved SVD algorithm to learning.py

* Update learning.ipynb

* Add files via upload

* Minor fixes

* Typo fix

* spacing in text.py

* information retrieval notebook section

* Added decisiontreelearner to notebook

* Added RandomForest

* Update nlp.py

* Update test_nlp.py

* Update nlp.ipynb

* Update text.py

* Update test_text.py

* Update text.ipynb

* 'sentences' to 'samples'

* Update learning.ipynb

* Update csp.ipynb

* Update games.ipynb

* Added pl_resolution to notebook

* Added pl_resolution and FolKB to notebook

* Update logic.py

* Update rl.ipynb

* Update search.ipynb

* Update learning.ipynb

* Update notebook.py

* Update .travis.yml

* Update games.ipynb

* Update games.py

* unigram char model + rename text to word models

* Update test_text.py

* Update text.ipynb

* remove duplicate assert

* Update logic.ipynb

* canvas -> notebook in games

* Rename canvas.py to notebook.py

* Update csp.ipynb

* Update mdp.ipynb

* add RandomVacuumAgent + CompareAgents

* set random.seed

* Update test_learning.py

* Update learning.py

* Update learning.ipynb

* Update learning.ipynb