Better error handling

[IngwiePhoenix]

https://github.com/Groterik/dynfload/blob/master/dynfload.h#L131-L135

Within these lines of code, you basically are outright ignoring an error that might occur during unload(). Now, that might not be too dramatic, but you probably should offer means to at least drop the error to STDERR if any.

#ifdef DYNFLOAD_LOG_ERROR
catch(Exception e) {
  std::cerr << e.what() << std::endl;
}
#else
catch(...) {}
#endif

So a user may do:

#define DYNFLOAD_LOG_ERROR
#include "dynfload.hpp"