Added concept node detection for the CFG (control flow graph).
Added Node class for the control flow graph (CFG).
Implemented use of Node.
Added quick and dirty parameter test:extractmethod to test extract method.
Added a contains check to prevent duple children or parents.
Added join (branch) afther a if.
Added DOT graph to the console.
Added flow back to allow flow of control to go back (loop).
Added flow back to allow flow of control to go back (loop) in StatementVisitor.
Added unit test for Node class.
Added test to test adding a child.
Added test to check if adding the same child twice is handled correctly.
Added test addFlowBackTest to NodeTest.
Added test addFlowBackSameTest to NodeTest.
Added getGraph method.
Added ControlFlowGraph class.
Added toDOTGraph() method.
Removed printDOTGraph() method because it is moved to ControlFlowGraph.
Renamed StatementVisitor to ControlFlowGraphVisitor and removed public (hidde class).
Added ControlFlowGraphVisitorTest unit test.