Always ask for positions in MPQ.scorer(); fencepost error in UnionDocsAndPositionsEnum posqueue sorting

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/lucene2878@1642079 13f79535-47bb-0310-9956-ffa450edef68
Pass postings flags from MultiPhraseQuery through correctly

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/lucene2878@1642089 13f79535-47bb-0310-9956-ffa450edef68
MemoryPostingsFormat.nextPosition() should return NO_MORE_POSITIONS when exhausted

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/lucene2878@1642091 13f79535-47bb-0310-9956-ffa450edef68
Fix SimpleTextReader nextPosition() impls

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/lucene2878@1642120 13f79535-47bb-0310-9956-ffa450edef68