New snowball stemmers (Irish gaelic and Czech) [LUCENE-4042]

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New stemmers have been added to snowball (Irish gaelic and Czech).

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Migrated from LUCENE-4042 by Dawid Weiss (@dweiss), updated May 09 2016

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Robert Muir (@rmuir) (migrated from JIRA)

We have the irish one already, Jim contributed that on #4956.

I verified the .sbl is the same and already removed our local copy.

We should add the Czech one imo. It differs from cz.CzechStemmer.java in
that it implements the more aggressive variant, stemming derivational
endings etc, so it gives users a choice.

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Chris M. Hostetter (@hossman) (migrated from JIRA)

bulk cleanup of 4.0-ALPHA / 4.0 Jira versioning. all bulk edited issues have hoss20120711-bulk-40-change in a comment

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Robert Muir (@rmuir) (migrated from JIRA)

rmuir20120906-bulk-40-change

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Steven Rowe (@sarowe) (migrated from JIRA)

Bulk move 4.4 issues to 4.5 and 5.0

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Uwe Schindler (@uschindler) (migrated from JIRA)

Move issue to Lucene 4.9.