SegmentMetadataQuery stuff:
- Simplify implementation of SegmentAnalyzer.
- Fix type names for realtime complex columns; this used to try to merge a nice type
name (like "hyperUnique") from mmapped segments with the word "COMPLEX" from incremental
index segments, leading to a merge failure. Now it always uses the nice name.
- Add hasMultipleValues to ColumnAnalysis.
- Add tests for both mmapped and incremental index segments.
- Update docs to include errorMessage.