CW's Markdown engine is inaccurate

[Voileexperiments]

Most basic example:

1. foobar
    - abc
    - def

should be rendered as:

1. foobar
   • abc
   • def

but in CW Markdown it's not rendered properly:

[anter69]

Just remove the leading spaces and it works as intended:

...although in this case, there is a different issue:

[Voileexperiments]

I don't think that's "work as intended": basically every Markdown engine in every other site would not break for first-level nested lists no matter how many spaces are in front of them. That's just the most basic Markdown rendering.

Yes, I mean basic, because there are more sophisticated usage besides that, and for like all of them the rendering just breaks, which is a pain to work with:

(also, note that syntax lighting is broken in the third case)

CW's Markdown rendering engine is just slightly less broken than StackOverflow's one. It seems that only Github's is up to the task to handle the need to make nested lists for really organized formatting properly.

(p.s: I edited the issue title to reflect to Markdown rendering in general)

[kazk]

Preview and actual is still inconsistent (#1640), but I believe this one can be closed. The server side engine now uses CommonMark with GitHub extension and it should be very similar to GitHub comments.