c++ style changes: use this-> for calling object's methods
c++ style changes: use this-> for calling object's methods

Co-authored-by: Paul Romano <a436801bae4f27296736e9545e95ef593e23fd3e@gmail.com>
amandalund/openmc,amandalund/openmc,amandalund/openmc,walshjon/openmc,walshjon/openmc,amandalund/openmc,walshjon/openmc,walshjon/openmc