We need to consider the implications of wide-strings passed to things like 
stoppers and such. Do we need to convert them to UTF8?

Pike Glue Classes we need to write:

Xapian::DateValueRangeProcessor	Handle a date range
Xapian::ErrorHandler	Decide if a Xapian::Error exception should be ignored
Xapian::ExpandDecider	Virtual base class for expand decider functor
Xapian::ExpandDeciderAnd	ExpandDecider subclass which rejects terms using two ExpandDeciders
Xapian::ExpandDeciderFilterTerms	ExpandDecider subclass which rejects terms in a specified list
Xapian::MatchDecider	Base class for matcher decision functor
Xapian::MatchSpy	Class for classifying matching documents by their values
Xapian::v102::NumberValueRangeProcessor	Handle a number range
Xapian::PositionIterator	An iterator pointing to items in a list of positions
Xapian::PostingIterator	An iterator pointing to items in a list of postings
Xapian::StringValueRangeProcessor	Handle a string range
Xapian::TermGenerator	Parses a piece of text and generate terms
Xapian::ValueRangeProcessor	Base class for value range processors


C++ Classes we need to write:

Pike-based stopper bridge.
Pike-based stemmer bridge.

Class for functor pass-thru.