[MAJOR IMPROVEMENTS] When using qpOases in DLP check for large negative...

[MAJOR IMPROVEMENTS] When using qpOases in DLP check for large negative objective value, which suggests likely unboundedness of the problem. Change signature of most methods of StaticEquilibrium class so that they return true if operation succeeded, false otherwise. Add tests of LP formulations against polytope projection. Add ifdef CLP_FOUND everywhere in the code so that solver CLP is now optional (still to fix the cmakelist though). Add documentation.