Would someone please provide some highlights for how the CommonMark flavor is different from the Gruber/Github/StackExchange flavors? I’m sure there’s a mountain of details that were previously unclear and now aren’t, but as an end-user of Markdown, the web page doesn’t make it clear what this changes for me.
What are the big things I have to start writing differently now? Have any of the “why can’t Markdown just do X sensibly?” quirks (e.g., line breaks in lists, or what kind of brackets to use in links, or underscores in words) been worked out? Where am I most likely to encounter divergence (on something I actually care about) between StackExchange or GitHub markdown and Standard Markdown? What (if any) new syntax features have been added?