Added BinaryNode.h

-Spli node into .h file
-Updated function declaration ++
-Also in this commit : added function for left-left rotation
Added Rotate_RR() and fixed Rotate_LL()

-Added Rotate_RR(), which is the same as Rotate_LL() just oposite
-Fixed both so that they copy the child from the node that becomes the
new head
	For right-right rotation, this is the left child of the new head
	For left-left rotation, this is the right child of the new head
-The child node above will be copied as a child of the old head
	For right-right rotation it will be the right child of the old head
	For left-left rotation it will be the left child of the old head
-Added test code

Note:
-head is the position of the note the rotation is applied to. I.E. the node which has
unbalanced sub trees ( one subree two levels deeper than the other as
per AVL balacne criteria. )
-It is passed in by reference so that when it changes, the value being
pointed at changes as well
-So if you do Rotate_RR( root->leftChild ); the node being pointed at by
root->leftChild; will be changed.
-In the aboce case, root->leftChild is the head
Improved Print_LevelOrder()

-Now adds nullptr instead of skipping nodes
-Counts number of nullptrs, if this is the same as number of nodes in
this level, the level is empty
-Will print '-' when a nullptr is encountered

Note
-This will print an extra line of only - for the last level
-There is some redundant / commented out code. The code is left without
deleting because the function might be updated to not print only '-' for
the last level.