Changes in version 5.1:

-- Added hybrid_types.hpp that implements hybrid values 
   (that use hardware types instead of GMP whenever possible)
-- Implemented MathSAT-like strategies for entering/leaving 
   unknowns selection for simplex pivoting.
-- Added configuration options for choosing unknowns selection stretegies.
-- In solver_configuration.hpp: now the default is to randomize 5% of decides,
   so for this reason, it is no longer needed to use '-c config.cfg' for 
   this default options (the config file is only needed when you want to 
   change the default behaviour of the solver).  See ./src/argosmt -l for
   the list of the supported configuration options and their default values.


Changes in version 5.11:

-- Optimized tableau by avoiding pivoting rows that express unconstrained
basic unknowns. 

Changes in version 5.2:

-- Implemented theory propagations in arithmetic_theory.?pp that propagate bounds
   for all unknowns (not only basic unknowns, as before). Parallel implementation
   is also provided.
-- Implemented parallel version of MathSAT-like unknown selection strategies.

