* Corrected issue with markdowns softbreaks
It wasn't respecting the $:/config/markdown/breaks setting.
It was effectively always "true".
Also, no more errors when encountering hardbreaks.
* Corrected introduced md bug
Made it so after each md type, accumulated text may be flushed.
* Changed convertNodes to use switch statement
It's faster, less text, easier to read, and now debuggers don't play
duck-duck-goose with every if-else block.
* whitespace text is no longer forgotten
* Fixed issue with text after md pattern and \n
Fixes#855 - albeit it’s a bit of a kluge. The internal format returned
by `markdown.toHTMLTree()` isn’t sufficiently well documented for me to
be confident that the new code is resilient to all the things that
might be returned.
