Expose .pot file width as an option

[MichaelChirico]

trafficstars

Allow users the flexibility to set the width directly (rather than using base's inconsistency or my default width=Inf setting)

[MichaelChirico]

This is easily doable with the API of write_po_file(), just need to put it in the signature of translate_package(). Still tabling for next release...