Added Fresnel integral code and tests to brl/bbas/bnl

This comes from Brown University's internal repository at LEMS,
at lemsvxl/basic/dbnl. This is part of an effort to contribute a new edge
detection code to the official VXL.

Author:    Caio SOUZA <caioc2bolado@gmail.com>
Supervised by: Ricardo Fabbri <rfabbri@lems.brown.edu>