When typing, in Live Preview, this plugin replaces straight apostrophes ' with typographic apostrophes ’, standard quotation marks " with French opening "« " or closing " »" quotation marks, and "-- " with em dashes "—".
When you type Enter, two Enters appear. I suggest using this function with Linter plugin, to autocorrect Markdown syntax.
From command palette, you can launch Apostrophes to replace all the basic apostrophes in a document.
On/Off buttons for all options.