Fix minor output bug and refine output.

Previously the substep summary reports were cumulative, misleading the user.
Also, made output a little more compact and readable, ensuring numbers line up
unless unusually many digits are needed for times and iteration counts.

opm/simulators/WellSwitchingLogger.cpp

@@ -140,7 +140,7 @@ void WellSwitchingLogger::logSwitch(const char* name, std::array<char,2> fromto,
             ss << "    Switching control mode for well " << name
                << " from " << modestring[WellControlType(fromto[0])]
                << " to " <<  modestring[WellControlType(fromto[1])]
-               << " on rank " << rank << std::endl;
+               << " on rank " << rank;
             OpmLog::info(ss.str());
 }
 #endif