#71 size for images <img> tag

[matusamiguel]

I have noticed that if you don't specify the size of an
image (<img width="" height="" ...>), pdfDoclet will
expand it to the size of the page, what is sometimes
not very good. Just specifying the real size of the
image in the <img> tag the problem is solved. But I
consider it would be better that pdfDoclet could
automatically get the image size (if not specified in
the tag)