JDiff report of changes between different versions of Lucene [LUCENE-1083]

I think that a helpful addition to the release process for Lucene would be [JDiff](http://www.jdiff.org) reports of the API changes between different versions. I am attaching reports of the differences between 1.9.1 and 2.2.0 and also between 2.1.0 and 2.2.0. The reports could be changed to only show the public methods. The start page is changes.html.

This is the Ant target I added to the top-level build.xml file in the JDiff directory to produce a report:

```

```

Disclaimer: I'm the author of JDiff

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Migrated from [LUCENE-1083](https://issues.apache.org/jira/browse/LUCENE-1083) by Matt Doar, updated Feb 28 2013
Attachments: [1083_1.patch](https://apache.github.io/lucene-jira-archive/attachments/LUCENE-1083/1083_1.patch), [1083_2.patch](https://apache.github.io/lucene-jira-archive/attachments/LUCENE-1083/1083_2.patch), [core-jdiff.zip](https://apache.github.io/lucene-jira-archive/attachments/LUCENE-1083/core-jdiff.zip), [jdiff_lucene_191_220.zip](https://apache.github.io/lucene-jira-archive/attachments/LUCENE-1083/jdiff_lucene_191_220.zip), [jdiff_lucene_210_220.zip](https://apache.github.io/lucene-jira-archive/attachments/LUCENE-1083/jdiff_lucene_210_220.zip)