feat(util/scoped_vec): add get_vec method
refactor(dsolvers/icp_solver): remove m_explanation
feat(dsolvers/icp_solver): add get_explanation method
feat(dsolvers/nra_solver): add m_explanation_stack
feat(realpaver/rp_constraint): mark used only if ctr is unfeasible
fix(CMakeLists.txt): rename CAPD to CAPD3
feat(CMakeLists.txt): use CAPD4
feat(dsolver/ode_solver): use CAPD4