This patch contains core changes so someone else needs to commit it.
Due to the incompatible #termDocs(null) behaviour at least MatchAllDocsQuery, FieldCacheRangeFilter and ValueSourceQuery fails using II since 2.9.
AllTermDocs now has a superclass, AbstractAllTermDocs that also InstantiatedAllTermDocs extend.
- II-tests made less plausable to pass on future incompatible changes to TermDocs and TermEnum
- IITermDocs#skipTo and #next mimics the behaviour of document posisioning from SegmentTermDocs#dito when returning false
- II now uses BitVector rather than sets for deleted documents