Also dismissed implementing colgroups for now - had it but didn't like the
added complexity for a very questionable benefit - i've actually never used
that feature of org tables...
- was missing spaces between attributes when rendering to org
- was duplicating attributes when rendering to html - now we join / replace
attributes depending on the name - for now only class & style are appended
... hopefully correctly
This will hopefully improve ease of developing (more granular test results) and
prepares us for adding example org->html renders for gh-pages
