First version of Markdown export plugin

[TW_Tones]

@Scott_Sauyet

But the trouble from a TW perspective is Markdown. If all we want out of our TW is Markdown content like we could have in ten thousand other applications, then all this will work fine. But TW has much more dynamic content than Markdown can handle. So if you have a wiki with lists, filters, macros, procedures, etc. used in displaying your content, it’s all quite a bit more challenging.

It is possible to first render the tiddler, applying markdown/WikiText and TiddlyWiki script to generate the result and only then capture the result. Currently out of the box this will be HTML, so if your target platform accepts HTML there is nothing more to do, however I believe there are new features in 5.4.0 that allow more robust parsing and return, so I would not be surprised if new conversion opportunities exist, and example may be converting the render to generate an intermediate markdown before rendering as HTML, allowing the intermediate result to be copied for pasting as markdown or into Pandoc.

I do believe we should make it a priority to be able to add tiddlywiki to the pandoc formats or at least have a path to enter the Pandoc ecosystem through markdown.

I note Pandoc does accept html input;

• The internals plugin allows you to view and copy the rendered html
• I have made a copy rendered html to clipboard button previously
• There will be issues with included media