[WIP] TRON solver for bound constrained QPs

CMakeLists.txt

@@ -90,6 +90,7 @@ file(GLOB UNO_SOURCE_FILES CONFIGURE_DEPENDS
    uno/ingredients/inertia_correction_strategies/*.cpp
    uno/ingredients/subproblem/*.cpp
    uno/ingredients/subproblem_solvers/*.cpp
+   uno/ingredients/subproblem_solvers/TRON/*.cpp
    uno/model/*.cpp
    uno/optimization/*.cpp
    uno/options/*.cpp

uno/ingredients/inequality_handling_methods/InequalityHandlingMethodFactory.cpp

@@ -28,6 +28,13 @@ namespace uno {
          }
       }
       // from now on, the problem has inequalities
+      /*
+      // bound-constrained problem: do not reformulate
+      if (problem.number_constraints == 0 && problem.has_bound_constraints()) {
+         return std::make_unique<NoInequalityReformulation>("bound-constrained method");
+      }
+      */
+
       const std::string inequality_handling_method = options.get_string("inequality_handling_method");
       // inequality-constrained methods
       if (inequality_handling_method == "inequality_constrained") {

uno/ingredients/subproblem_solvers/SubproblemSolverFactory.hpp

@@ -11,6 +11,7 @@
 #include "InverseNewtonSolver.hpp"
 #include "QPSolverFactory.hpp"
 #include "WoodburyEQPSolver.hpp"
+#include "TRON/TRONSolver.hpp"
 #include "ingredients/subproblem/Subproblem.hpp"
 #include "options/Options.hpp"
 #include "tools/Logger.hpp"
@@ -52,6 +53,14 @@ namespace uno {
             return subproblem_solver;
          }
       }
+      /*
+      // if only bound constraints, allocate bound-constrained solver
+      else if (subproblem.number_constraints == 0 && subproblem.has_bound_constraints()) {
+         auto subproblem_solver = std::make_unique<TRONSolver>();
+         subproblem_solver->initialize_memory(subproblem);
+         return subproblem_solver;
+      }
+      */
       // if no inequality constraint and no trust region, allocate EQP solver
       else if (!subproblem.has_inequality_constraints() && !subproblem.has_bound_constraints() && !uses_trust_region) {
          if constexpr (std::is_same_v<HessianType, InverseLBFGSHessian>) { // unconstrained