Adaptive Frame Of Reference [LUCENE-2886]

We could test the implementation of the Adaptive Frame Of Reference [1] on the lucene-4.0 branch.
I am providing the source code of its implementation. Some work needs to be done, as this implementation is working on the old lucene-1458 branch.
I will attach a tarball containing a running version (with tests) of the AFOR implementation, as well as the implementations of PFOR and of Simple64 (simple family codec working on 64bits word) that has been used in the experiments in [1].

[1] http://www.deri.ie/fileadmin/documents/deri-tr-afor.pdf

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Migrated from [LUCENE-2886](https://issues.apache.org/jira/browse/LUCENE-2886) by Renaud Delbru, updated May 09 2016
Attachments: [LUCENE-2886_simple64_varint.patch](https://apache.github.io/lucene-jira-archive/attachments/LUCENE-2886/LUCENE-2886_simple64_varint.patch), [LUCENE-2886_simple64.patch](https://apache.github.io/lucene-jira-archive/attachments/LUCENE-2886/LUCENE-2886_simple64.patch), [LUCENE-2886.patch](https://apache.github.io/lucene-jira-archive/attachments/LUCENE-2886/LUCENE-2886.patch) (versions: 3), [lucene-afor.tar.gz](https://apache.github.io/lucene-jira-archive/attachments/LUCENE-2886/lucene-afor.tar.gz)