Moving Grid to Utils (aimacode#540)

* Delete test_grid.py

* Delete grid.ipynb

* Delete grid.py

* Move grid functions to utils

* Move grid tests to utils

* Update agents.py

* Update mdp.py

* Update search.py

Author: antmarakis

agents.py

@@ -35,7 +35,7 @@
 #
 # Speed control in GUI does not have any effect -- fix it.
 
-from grid import distance_squared, turn_heading
+from utils import distance_squared, turn_heading
 from statistics import mean
 
 import random