Things to do:

 - Write documentation for how to use libstemmer (as opposed to how stemming
   algorithms themselves work).
   Currently, the documentation in the include/libstemmer.h header file is
   pretty clear and comprehensive, but an overview document wouldn't go amiss.

Things that would be nice to include at some point.

 - Add version numbers to each stemming algorithm, and allow the interface to
   request a specific version of the stemming algorithms.  Default to providing
   the latest version of the algorithm.