Added a cat as an obstacle for the mouse in Maze. Simply replaced one of the random tiles with a cat.
Removed the additional tiles_mouse_2.png
Revert "Removed the additional tiles_mouse_2.png"

This reverts commit d2d3db631ed6dc58e815b7bc9cd2a2826688e76d.
Revert "Revert "Removed the additional tiles_mouse_2.png""

This reverts commit 587222f52cf8d1f21f200193ab821ae3323ad679.
Reverting the mouse changes.
Revert "Added a cat as an obstacle for the mouse in Maze. Simply replaced one of the random tiles with a cat."

This reverts commit 8178ff4535bc74024a6a57a5d802fbe3cea2ca6b.
Added the obstacles in mouse and cheese. The obstacle still shows there is a path, but when you tend to walk on it, it shows as if you hit a wall.
Corrected the description for normalize function in Karel.
Removed the redundant code in rending the maze (normalize).
Merge pull request #30 from nanan9177/mooc

Added obstacles for mouse and cheese in Maze