== New: Text formatting via macros

I (ChrisSiebenmann) found myself with a genuine need for text set in
HTML <strike>. Rather than try to invent a formatting setup for this
that did not make me cringe, I just punted to the easy solution: macros
that do text formatting.

So, DWiki now has grown the new macros:
* _ST_ for the font styles DWiki didn't already have.
* _C_ for character entities, and _ShowCharEnts_ to show the named
  entities we support.
* because I was there anyways, _AB_ for <abbr>, so I could have those
  cute inline abbreviation expansion things. Tragically <abbr> is not
  supported by IE 6 and less, so _AB_ may quietly change to generating
  <acronym> someday.
* and finally, _IMG_ to generate <img>. Width, height, and alt text is
  mandatory, and there is a hacky way to also roll title text in too.
  (Title text is optional.)

Through special black magic, _ST_, _C_, and _AB_ can be used in comments
(the omission of _IMG_ is deliberate). In theory this lets a commenter
cause character set explosions, but in practice a bad commenter can just
write UTF-8 directly (UTF-8 is the common and only sane character set
choice, so).

Implementing these as macros means that they have some limitations. You
can't nest _C_, _AB_, or a differently styled _ST_ inside an _ST_, and
currently none of them can be done inside link text (_![[....]]_).

These macros are a bit of a hack. It's relatively easy to implement
bits of HTML this way, but I'm not sure if it's good design overall.