With the removal of the (standalone) Firefox building code in PR 9566 (a year and a half ago), these files are now completely unused in the GitHub repository[1].
Hence it doesn't really seem necessary to keep fetching them with `gulp importl10n`, and the existing files in the `l10n` folder can also be removed (thanks to version control, they're easy enough to restore should the need ever arise).
The patch also allows an additional simplification, for the `gulp locale` and `gulp mozcentral` commands, since it's now possible to stop writing `l10n` files to the `extensions/firefox/` folder and instead just copy them similar to other build targets.
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[1] They're obviously still used in `mozilla-central`, for fallback messages displayed through `PdfStreamConverter.jsm`, but that doesn't make it necessary to keep them *here* as far as I'm concerned.
With the removal of the (standalone) Firefox building code in PR 9566 (a year and a half ago), these files are now completely unused.
Hence it doesn't really make sense to keep building them as part of `gulp locale`, and the existing files in the `l10n` folder can also be removed (thanks to version control, they're easy enough to restore should the need ever arise).
Line 56-58: "Gegen den Uhrzeigersinn" is shorter and more common than "Entgegen dem Uhrzeigersinn" (http://de.wikipedia.org/wiki/Drehrichtung)
Line 60-63: "Hand-Werkzeug" is also used in Acrobat
Line 124,133,..: "PDF" is not a noun. Acrobat, Wikipedia use "PDF-Datei" (="PDF file") instead of "PDF".
The English translation sounds just as bad: "An error occurred while loading the PDF.", "The PDF is not fully loaded for printing."
