Fixed issue with binary tree, where a null node could overlap another node.
Fixed issue with binary tree, where a null node could overlap another node.

RJFreund/OpenDSA,RJFreund/OpenDSA,RJFreund/OpenDSA,vkaravir/JSAV,RJFreund/OpenDSA,RJFreund/OpenDSA,RJFreund/OpenDSA,RJFreund/OpenDSA,vkaravir/JSAV,RJFreund/OpenDSA