introduce hard-coded max time step size

dune/tectonic/time-stepping/adaptivetimestepper.cc

@@ -73,7 +73,7 @@ int AdaptiveTimeStepper<Factory, ContactNetwork, Updaters, ErrorNorms>::coarsen(
 
     const auto& currentNBodyAssembler = contactNetwork_.nBodyAssembler();
 
-    while (relativeTime_ + relativeTau_ <= 1.0) {
+    while (relativeTime_ + relativeTau_ <= 1.0 && relativeTau_ < 0.1) {
       //std::cout << "tau: " << relativeTau_ << std::endl;
 
       setDeformation(current_);