Allow the ~() of StopWatchSession() to throw to prevent...

Allow the ~() of StopWatchSession() to throw to prevent Progress::Context::abort(), which can be potentially called by DEB_line(), from terminating.

Debug/DebTime.hh

@@ -20,7 +20,7 @@ public:
     sw_.start();
   }
 
-  ~StopWatchSession()
+  ~StopWatchSession() noexcept(false)
   {
     // TODO: implement "prettier" DEB out if seconds turn into minutes/hours/etc
     DEB_line(deb_lvl_, sssn_name_ << " took " << sw_.stop()/1000.0 << " s.");