First version of Markdown export plugin

@cdaven
Can there be an additional option like a Realtime Markdown Convertor tiddler

  1. At the top of this convertor tiddler, there shall be a tiddler selector with search box (where we can type the tiddler name) or select widget option to select the tiddler converted to be markdown.
  2. Once the tiddler is selected, a side by side editor opens up below the selector showing the wikitext format on the left side and markdown format on the right side.
  3. At the bottom, there shall be a export as md or copy to clipboard buttons.

Is it doable?