Highlighter fixes
Return type of StrIter_Clone
Allow NULL arguments to StrIter_substring
Introduce StrIter_Starts_With_UTF8
Introduce StrIter_Ends_With
Convert rest of Highlighter to StringIterators
Convert QueryLexer to StringIterator
Eliminate SStr_Chop in IndexManager
Convert Index::Segment to StringIterator
Convert QueryParser to StringIterator
Eliminate SStr_Nip in CompoundFileReader
Eliminate SStr_Nibble in Store::FSFolder
Convert Store::Folder to StringIterator
Convert Store::Lock to StringIterator
Convert Store::SharedLock to StringIterator
Convert Util::IndexFileNames to StringIterator
Convert Util::Json to StringIterator
Eliminate SStr_Nibble in Clownfish::Test::TestObj
Convert Clownfish::VTable to StringIterator
Remove String methods Nip, Nibble, Chop, and Truncate