Gecode SVN revision 14227.
Use Gecode as a  solver.

It is now time to use multiple files….
Do not run Gecode tests.
Refactor out easy-ip-internal.h
Refactor out integer_programming.cpp.
Refactor out satisfiability.cpp
Refactored out constraint_programming.cpp.
“Round” when using Gecode.
Create Gecode model from IP description.
IP::next_solution with Gecode.