This is an academic exercise to show how simple a search engine
can be. The original inspiration for this was Jean Adams' Castilleja
Programming Think-Tank, which aims to expose new programmers to the
power of computing. Perhaps this minimal "search engine" can serve
as a jumping-off point for student projects?

Usage:

1. Construct a forward index:

   $ ./forwardindex.py ./test/ > fi.dat

2. Construct an inverted index:

   $ ./reverseindex.py < fi.dat > ri.dat

3. Run some queries

   $ ./query.py ri.dat
   fourscore and seven
   vmware
   woozle
   fraternité
   FRATERNITE
   인간은
   ^D

   fourscore and seven

                                                                             test/a
   vmware

                                                                      test/subdir/1
                                                                             test/b
   woozle

   fraternité

                                                                             test/c
   FRATERNITE

                                                                             test/c
   인간은

                                                                             test/d

There is no ranking, nor much life-support for ranking to be found here.
Again, this is a pedagogical exercise to show how easy it can be to
construct something that is recognizable as a search engine.