Move Lucene.NET out of incubation

git-svn-id: https://svn.apache.org/repos/asf/lucene/lucene.net/tags/Lucene.Net_1_9_1@897424 13f79535-47bb-0310-9956-ffa450edef68
tree: 492f3fde5e12583a9400e6c73f36f75fabe34ae5
  1. contrib/
  2. src/