Major Description
After the big spans overhaul in LUCENE-6308, we can speed up SpanNearQuery a little more:
- SpanNearQuery defaults to collectPayloads=true, but this requires a slower implementation, for an uncommon case. Use the faster no-payloads impl if the field doesn't actually have any payloads.
- Use a simple array of Spans rather than List in NearSpans classes. This is iterated over often in the logic.