Datainput: implement vector support for Evaluator

QJSValue that is used to feed datainput values to JS engine is not natively supporting Vector datatypes. In order to use Vector3 type datainputs as source data for evaluator, we probably have to manually break down the user-given JS string and decompose vec3-type argument to array type. Before JS func call, we also need to convert actual QVector3D values to array type.