bug: clear data state from unused data

when changing the shape of the form, the data state remains untouched; immediate export will result in the state of the previous shape being exported

two possible solutions:

1. clear data state from unused fields on shape change => data of unused fields is lost
2. clear data state from unused fields on export

for the implementation of the filtering, use the filter function from the effect that filters quads from the remoteDataStore as an example; beware, this function filters on the set of all PropertyShapes's paths in the schema and thus makes it possible to use it even on shape selection/change. => prefer the 2. solution and implement a filter on the PropertyShapes's of the selected NodeShape. This filter should also be applied before calling the "handleSave" function handed down from the parent component of ROGER(-Core) (see handleClickSave)