Generalized Bezout numbers and linear-product start systems.

Four types of start systems are implemented, based on total degree,
m-homogeneous, multi-homegenous, and generalized Bezout number.

1. Total degree 

     startsys           Total_Degree_Start_Systems

2. m-homogeneous Bezout number

     sets               Sets_of_Unknowns
     sets_io            Sets_of_Unknowns_io
     degsets            Degrees_In_Sets
     partsets           Partitions_of_Sets_of_Unknowns
     partsets_io        Partitions_of_Sets_of_Unknowns_io
     mhombez            m_Homogeneous_Bezout_Numbers
     rps                Random_Product_System
     rps_io             Random_Product_System_io
     mhomstart          m_Homogeneous_Start_Systems
     intehom            Interpolating_Homotopies
     drivinho           Driver_for_Interpolating_Homotopies
     drivmhom           Drivers_for_m_homogenization

3. multi-homogeneous Bezout number

     ds                 Degree_Structure
     rpss               Random_Product_Start_Systems
     drivmuho           Drivers_for_Multi_Homogenization

4. Bezout number based on set structure

     ss                 Set_Structure
     ss_io              Set_Structure_io
     generate           Generate
     persets            Degree_Sets_Tables
     crpss              Construct_Random_Product_Start_System
     drivss             Drivers_for_Set_Structures
