Resolve "Problem::getState(structure) doesn't care about structure"

Closes #343 (closed)

include/core/common/time_stamp.h

@@ -290,8 +290,6 @@ inline double TimeStamp::operator -(const TimeStamp& ts) const
     return double((long int)(time_stamp_nano_ - ts.time_stamp_nano_))*1e-9; // long int cast fix overflow in case of negative substraction result
 }
 
-//static const TimeStamp TimeStampInvalid() {return TimeStamp(-1.0);}
-
 } // namespace wolf
 
 #endif