[dev-context] removing BibTeX auxiliary files with --purgeall

Hello Hans and Taco, may I also add the request that temporary files created by BibTeX are deleted automatically by --purgeall? That is, *.blg *.aux It'll probably be wise to keep the *.bbl file :-) Although it is created automatically by the BibTeX run I need to tweak it manually at times ... Best wishes, Oliver P.S. I cannot test this with MkIV at the moment but MkII doesn't delete those files for sure ...