Misplaced files in pgf-periodictable package

[Karl Berry]

Hi Hugo,

    `translations/lang.undefined.tex' 

Please rename your translation files to something with
"pgf-periodictable" or "pgfPT" in the name (as you've done before...),
instead of the generic lang.{undefined,nl}.tex. All filenames in the
runtime tree have to be globally unique for reliable searching.

Thanks,
Karl