committed graphicx.4ht html4.4ht usepackage.4ht to TL (r45571). Thanks.

I've added support for TikZ externalization and for PDF image inclusion.

The externalization supports means that TikZ will not try to externalize the images with tex4ht compilation, saved images will be used instead. So it is necessary to compile the document using (pdf|lua|xe)latex first, with -shell-escape option. The externalized images will be included as PDF.

This is connected with the second new feature, which is PDF image support. PDF images will be converted to some supported format, I've added support for SVG support as default. Inkscape is used for the conversion. New configuration, PdfConvert have been added. It has two arguments, first is the image format which should be used, the second is a command used for conversion.

This is the default configuration:

\Configure{PdfConvert}{svg}{"inkscape -z -f '\Gin@base.pdf' -l '\Gin@base.\a:PdfConvert'"}

I think we can add more configurations and use the command line options for choosing among them.

The main reason to use the externalization instead of the default TikZ support for tex4ht, is that it has better support for text nodes and more TikZ features. And also the compilation speed should be better.