Bug bibdoiadd - does not accept non-ASCII keys

[pauloney]

The following record:

@article{Rodriguez-Bosch-Gascón-2008,
    author = {Rodríguez, E. and Bosch, M. and Gascón, J.},
      year = {2008},
     title = {A networking method to compare theories: Metacognition in problem solving reformulated within the anthropological theory of the didactic},
   journal = {ZDM - the International Journal on Mathematics Education},
    volume = {39},
    number = {2},
     pages = {287--301},

}

when processed by bibdoiadd produces the error:

$ bibdoiadd -c bibdoiadd.cfg -e 0 tmp.bib
Cannot understand entry: Can't locate object method "print" via package "BibTeX::Parser::Entry" at 
/usr/local/texlive/2017/bin/x86_64-linux/bibdoiadd line 191, <GEN0> line 20.

because of the non-ASCII character used in the key. This is not allowed by traditional BibTeX, but it is by many of BibTeX extensions including BibLaTeX, so one should be able to process records with it.