[Groff] patches to www.tmac

[Werner LEMBERG]

I've applied some patches from Gaius for www.tmac, slightly
modified.  Instead of his original names <FOO and FOO> I added
FOO-BEGIN and FOO-END for consistency.  The new macros are

  PNG-IMAGE to include a pgn image (and with automatical conversion
  to EPS if -Thtml isn't used).

  MARGIN-PNG-IMAGE to include a png image in the margin.

  HTML-H-BEGIN and HTML-H-END to define a header block.

  DROPCAP for producing dropcap characters.

Additionally, the parameters of IMAGE have changed from `r', `l', and
`c' to `-R', `-L', and `-C'.

My suggestion is to test all features in www.tmac, regardless of
optimal syntax etc. -- this is alpha stuff!  After things are
consolidating, we should produce a new macro package named `w3.tmac'
which will be cleanly designed.

Please test.


    Werner