Standards-based analyzers implemented with JFlex.

The `org.apache.lucene.analysis.standard` package contains three fast grammar-based tokenizers constructed with JFlex:

- `StandardTokenizer`: as of Lucene 3.1, implements the Word Break rules from the Unicode Text Segmentation algorithm, as specified in Unicode Standard Annex #29. Unlike `UAX29URLEmailTokenizer`, URLs and email addresses are not tokenized as single tokens, but are instead split up into tokens according to the UAX#29 word break rules.
  `StandardAnalyzer` includes `StandardTokenizer`, `StandardFilter`, `LowerCaseFilter` and `StopFilter`. When the `Version` specified in the constructor is lower than 3.1, the `ClassicTokenizer` implementation is invoked.
- `ClassicTokenizer`: this class was formerly (prior to Lucene 3.1) named `StandardTokenizer`. (Its tokenization rules are not based on the Unicode Text Segmentation algorithm.) `ClassicAnalyzer` includes `ClassicTokenizer`, `StandardFilter`, `LowerCaseFilter` and `StopFilter`.
- `UAX29URLEmailTokenizer`: implements the Word Break rules from the Unicode Text Segmentation algorithm, as specified in Unicode Standard Annex #29. URLs and email addresses are also tokenized according to the relevant RFCs.
  `UAX29URLEmailAnalyzer` includes `UAX29URLEmailTokenizer`, `StandardFilter`, `LowerCaseFilter` and `StopFilter`.