Make stern brocot tree sequence by level.

[yosshi4486]

if I give '10' to a function, it returns the sequence owns 1024 proper nodes of stern brocot tree aligned left to right.

[yosshi4486]

Because sbtree is binary tree.

[yosshi4486]

or 'makeSternBrocotTree(numberOfNodes: Int)' determines the actual level and returns least node.

[yosshi4486]

and makeNodesSequenceOfSpefifiedLevel(_ level: Int)

[yosshi4486]

class SternBrocotTree {

    private(set) var nodes: [SBTreeNode]

    init(heightOfTree: Int) { }

    init(level: Int) { }

   func nodes(at level: Int) -> [SBTreeNode]? { }
}