[Groff] some grohtml issues

[Werner LEMBERG]

Gaius,


please document the .HTML-IMAGE-{START,END} macros.

Another issue is that there are nasty error messages if the image is
larger than the page.  For example, change this

  \v'-0.75i'\h'2.0i'\s[60]\*[GNU] Troff\s0

to this

  \v'-0.75i'\h'3.0i'\s[80]\*[GNU] Troff\s0

in webpage.ms -- I get the following error message:

  Calling `pnmcut 100 138 797 168 < /tmp/groff-page-oWMkU8
          | pnmcrop -quiet
          | pnmtopng -background white -transparent white
          > img/webpage1.png ' returned status 256

In general I think that image generation for HTML shouldn't have any
size restrictions at all -- browswers can scroll.

Finally, there is a bug in the removal of temporary files -- at least
for me, the stuff from the last image in a grohtml run stays in /tmp.


    Werner