Ctypes allows to import dynamically linked libraries into a Python session.

For the Python scripts to work, the file ../../lib/libPHCpack,
for the proper platform (extension .so, .dylib, or .dll) must be present.

---------------------------------------------------------------------------
file name               : description
---------------------------------------------------------------------------
version                 : gets the PHCpack version string
---------------------------------------------------------------------------
dimension               : dimension of the polynomial systems
polynomials             : set and get of polynomials
solutions               : exports operations on solutions
volumes                 : mixed volumes and stable mixed volumes
solver                  : exports the blackbox solver
examples                : runs some examples
---------------------------------------------------------------------------
series                  : series expansions of solution curves
---------------------------------------------------------------------------

The directed acyclic graph shows the module dependencies:

   version
      |
      +----------------------------> solutions         
      |                                  |
      +--> dimension                     |
      |        |                         |
      +--------+--> polynomials          |
      |        |         |               |
      +------------------+--> volumes    |
      |        |         |       |       |
      +--------+---------+-------+-------+--> solver 
      |        |                                |
      +--------+--------------------------------+--> examples

At the root is the version module.  If version.py works,
then the interfacing with libPHCpack works.
Four other modules are needed for the blackbox solver.
