seft - search engine for text, APE build with mkfile.

Seft takes a set of query terms and a set of files as arguments and, using
a locality-based similarity heuristic, determines word locations within the
files that are of interest with respect to the query.  The user is then
presented with a sequence of windows of text, the first window surrounding
the most relevant location, the second window surrounding the next most
relevant location and so on.  Both the number of windows presented and the
size of the window can be specified as parameters to seft.  In addition,
the user can specify whether to apply case-folding and/or stemming to the
query terms and the text files.