Added WalkSAT

Multiple updates to agents.py (WumpusEnvironment and XYEnvironment)

Fixed Outdated Idioms in Python 3 Port

IPython Notebook for logic.py

Implemented arrow shooting in Wumpus World. Wumpus Environment is now complete.

doccument -> document

In hindsight, the variable name "doc" implies we are manipulating the
document itself when, in reality, we are manipulating the index of the
document. "docid" better expresses this concept.

Added self to argument

This change is for consistency.

Cast was not needed since the return value was already being cast. Query
function changed to use heapq.nlargest() for simplicity

Fixed bug where dead agents still get to act (Environment)
Improved Direction class to ease 2D Movements (Direction)
Implemented an easier way to iterate with and without walls (XYEnvironment)
Added is_inbounds() method to check if location is within the width and height. Works within walls also. (XYEnvironment)
Multiple Minor Fixes(agents.py)

Apparently, set() does not equal {}

Problems fixed:
Replaced cmp: 1 instance in line 323 of search.py
Convert set() to {}: 3 instances in line 29 of MDP.py, line 181 and 215
of search.py
Convert .sort() to sorted(): 1 instance in line 150 of text.py
Cast map to list: 1 instance in line 47 of grid.py

WumpusEnvironment

Fix a minor error to arguments of flake8 in Travis configuration file

Moved Tests for MDP into Test File

Add tests for the Wumpus World