IndexManager implementation taking advantage of the Near-Real-Time
features of Lucene.
When using this work mode the IndexWriter does not need a full
flush at the end of each operation: new IndexReaders are able to
inspect the unflushed changes still pending in the IndexWriter buffers.
This improves write performance as the IndexWriter doesn't need
to commit as often, but has two limitations:
unsaved index data might be lost in case of crashes