Improved support for case- and diacritics-sensitivity.

* Added TextPatternSensitive to specify case/diacritics sensitivity
preferences for a query
* Made sure atomic queries (term, prefix, regex, etc.) are lowercased
iff case-insensitive search is active
* Replaced fieldName parameter to translator methods with
TPTranslationContext, which contains more details about the current
"environment" (such as the preferred case/diacritics-sensitivity)
* Added method IndexStructure.print() which dumps the index structure in
human-readable form
* Added method IndexStructure.getDocumentTitleField() which guesses
which metadata field contains the document title (to use for display)
* Removed TextPatternTranslatorQuery
Added filter, sensitive, doctitle and structure commands to QueryTool

* filter filters on metadata (Lucene query syntax)
* sensitive on|off controls case/diacritics sensitivity
* doctitle on|off controls whether to show document titles in results
* structure shows the index structure
Fixed TextPatternWithin not rewriting its clauses.

Made TextPatternWithin derive from TextPatternCombiner (like
TextPatternContaining).