Also added a “description” field for wiki folders.
Right now there’s too many editions listed. I think we should by
default only list editions whose `tiddlywiki.info` file has
`showInListings` set to `true`, and have an `--editions all` command
that lists everything.
@pmario please could you check that the editions in your
`TIDDLYWIKI_EDITION_PATH` are correctly listed?
Getting rid of the old widget mechanism files finally gives us a payoff
for all the refactoring. Still a bit of tidying up to do, and we need
to re-introduce the animation mechanisms.
To start with, we move the current stylesheets into a theme plugin
called "Snow White". Wikis have to specify at least one theme in their
`tiddlywiki.info` file. Next we'll add a mechanism for switching
between loaded themes
