Store the polynom in a property - Feature request

[ulrich06]

Currently, the polynomial value of a PolynomialNode is accessed by parsing the polynomial attribute of the JSON generated by the toString method
eg. {"world":0,"time":1468504965,"id":10"polynomial":"29.373022419094397+(-0.019802106705884497*t)"}

It would be useful to retrieve directly this value through a method or a property

eg.thePolynomialNodeInstance.get("polynomial") or thePolynomialNodeInstance.getPolynomial()