Treatment and representation of solution components with PHCv2.3.21

This directory was new in release 2.1 and under continueing development.
Release 2.2 offered a blackbox factorization for multivariate polynomials,
a first implementation of diagonal homotopies in extrinsic coordinates,
and a first attempt for an equation-by-equation solver.
Release 2.3 introduced intrinsic coordinates to sample and to intersect
varieties.  The subdirectory Solver was added in release 2.3 and contains
a preliminary version of a new equation-by-equation solver.

The organization of the library is organized as follows:

  Components           : 6. numerical irreducible decomposition 
     |-- Samplers      : 6.1 computing witness points
     |-- Interpolators : 6.2 finding equations for components
     |-- Factorization : 6.3 factorization into irreducible components
     |-- Decomposition : 6.4 sequence of homotopies to filter and factor
     |-- Solver        : 6.5 incremental equation by equation solver

The goal of the numerical irreducible decomposition is to decompose the
solution sets of various dimensions and degrees into irreducible components.
