Exploitation of permutation symmetry to construct symmetric homotopies.

If the polynomial system is invariant under permutations of its unknowns,
then it suffices to compute the generators of the solution set.
This is accomplished by the construction of a homotopy that has the
same symmetric structure as the polynomial system.

1. Permutations, symmetry groups and equivariant systems :

     perms              Permutations
     permops            Permute_Operations
     symgrp             Symmetry_Group
     symgrp_io          Symmetry_Group_io
     sbsymgrp_io        Symbolic_Symmetry_Group_io
     equpsys            Equivariant_Polynomial_Systems

2. Symmetric linear-product start systems with drivers :

     sym_ss             Symmetric_Set_Structure
     lsymred            Linear_Symmetric_Reduce
     templates          Templates
     orbits             Orbits_of_Solutions
     orbits_io          Orbits_of_Solutions_io
     drivgrp_io         Drivers_for_Symmetry_Group_io
     drivorbi           Drivers_for_Orbits_of_Solutions
     drivsss            Driver_for_Symmetric_Set_Structures

3. Data structures for symmetric lifting :

     faceperm           Permutations_of_Faces
     facesypo           Faces_of_Symmetric_Polytopes
     gencells           Generating_Mixed_Cells

4. Symmetric integer and floating-point lifting :

     symlift            Symmetric_Lifting_Functions
     symrand            function Symmetric_Randomize
     sympolco           Symmetric_Polyhedral_Continuation
     symbkk             Symmetric_BBK_Bound_Solvers

5. Drivers and target routine :

     drivsyml           Driver_for_Symmetric_Lifting
     mainsmvc           mainsmvc, as called by phc
