Scott SPPF algorithm for Earley item derivation #90
Description
The ItemDerivationVisitor may be able to be optimized using the Scott SPPF algorithm.
https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.1049.562&rep=rep1&type=pdf
This item doesn't block us from releasing 3.1.0, but it would be nice to consider eventually.