Added __toString(), setLeftOperand() and setRightOperand() methods to BinaryOperationNode, and renamed getLeft() and getRight() to getLeftOperand() and getRightOperand().
Added setAbstract(), setFinal(), and setExtends() methods to ClassNode.
Added setAbstract(), setFinal(), and setStatic() methods to ModifiersNode.
Added setOperator(), setOperand() and __toString() methods to UnaryOperationNode.