#92 OBO dump refs rendering

[Andy Deans]

Not sure this is a bug, exactly, more like a feature tweak. The obo dump doesn't load properly in OBO edit, and one problem is the rendering of of references such that they include non-URI characters:
[mxref:43472 Masner, L., and J. L. García. 2002., DOI: "", ISBN: "", ""]
Maybe we could just render the mx id?
[mxref:43472]
DOI or ISBN would be better, but we don't have those for very many refs (in our project at least).