new tools VTK2TIN, TIN2VTK

as titled
As far as I can see this utility does not output errors because you do not pass the required error-vector:
    readTIN(std::string const& fname, std::vector<GeoLib::Point*> &pnt_vec, **std::vector<std::string>* errors**)
and no error messages are currently output in the TIN-interface itself. 

yes, you can also output this in the read function, I was just concerned because imo the function currently just exits without letting the user know why. if you don't think it is necessary to output errors for this little utility because it is for internal use only, this is also okay.