Changes 4.31:
* The core LP solver based on the dual simplex method was
  re-implemented and now it provides both phases I and II.

* New API routines.

* For description of these new routines see the reference manual
  included in the distribution.

* The following API routines are deprecated:
  lpx_scale_prob, lpx_std_basis, lpx_adv_basis, lpx_cpx_basis.

* Necessary changes were made in memory allocation routines to
  resolve portability issues for 64-bit platforms.

* New version of the routine lpx_write_pb to write problem data
  in OPB (pseudo boolean format) was added to the package.

* Two new makefiles were added to build the package for 32- and
  64-bit Windows with Microsoft Visual Studio Express 2008.

* Two new makefiles were added to build the package with Digital
  Mars C/C++ 8.50 and Open Watcom C/C++ 1.6 (for 32-bit Windows).

(adam)