Grid class updated. Read description

List of Changes:
-Added a shoot() method that actually works now. Some comments are present in the code, read those for more detail
-Added void fixTheNull() method that cleans up a null space left from shooting because I wanted to make sure the ninja was dead
-Added boolean ifNinjaPlaceIsEmptyCell() returns if the current ninja in for loop has been shot or not
-Modified shootDirection() method to not be retarded
-Modified moveNinjas() method, new if statement in the do-while loop to make sure if the ninja is dead, hasMoved = true; so the next ninja can be checked to move.
-Modified killCheck() method, added an if statement that will check if they have been shot or not, if they havent; they do w/e it was ninjas do. else nothing else happens.
-Fixed an issue with grid being printed twice.
-Fixed issue where shooting something leave that part of the grid "isSeen" 
-Fixed issue where shooting with an object in the way causes nothing to happen and loop ends prematurely

Known Issues
-Ninjas sometimes combine into a super ninja where 2 ninjas occupy a spot and if u shot one, the other would appear as invisible until the ninja gets to move thus surprise attacking your butthole

What is needed left
-We need a win condition, when briefcase is found you win. Someone put that in, it should be easy.
-When shooting, ammo doesnt disappear; there is a shoot method in the Taha class. Someone plz put that method in somewhere so that when the player shoots, they lose ammo.
-Also, we need something to prevent the player from shooting if ammo <= 0
-We need a proper UI b/c the one im using is a dummy UI to just compile the game. (I will upload code of my version of UI, but keep Taha's version because it's prettier. Both codes will be available in the UserInterface class. Taha's code will be encased in // because his code doesnt include the option to shoot.)
-Also adding my version of the main class along side Taha's version, ultimate we'll use Taha's version b/c its fancy. For now, Taha's code will be encased in // for functionality purposes

If there are any other bugs you find, please let everyone know.