Reducing TreeNode size

[hongjisung]

Problem :
this tree data structure has a large node size than other npm packages.
And 'insert' method is relatively slower than 'erase' method.
I think the reason of above situation is that 'insert' method handles node object creating and it affects to efficiency.

Unlike other packages, there are some additional elements in TreeNode.

1. point parent node.
2. get/set method.
3. getPrev/getNext method.

but,

1. is useful for backtracking.
2. is good for knowing access restrictions.
3. is good for acture use or method chaining.

how to treat this problem?