[tex4ht] Output directory

[Karl Berry]

    BTW, does have somebody a handy makefile (or is there any other
    way?) to delete the text4ht files and remnants in the original dir?

Not sure how useful it'll be, but for the TL documentation, I remove
these:

clean:
	rm -f *.aux *.log *.blg *.toc *.out *.lot tex4ht.ps *.4*
	rm -f *.xref* *.lg *.idv *.out *.otc *.tmp tmp.*
	rm -f $(doc).dvi $(doc).ps

realclean: clean
	rm -f $(doc).pdf
	rm -f *.html *.htm $(doc).css *.gif *.jpg