ZF-4362: skipData interpretaion, skipTo method implementation.
each term within an index has a list of matched documents. This list may be large enough and it may take a long time to load it.
This list also has some additional subindex known as "skip data". This info allows to check directly if some document matches specified term.
Zend_Search_Lucene should read "skipData" info, "understand" it and provide an API for filtering termDocs requests in some way.