Allow headings to not be markdown headings

[evanthegrayt]

Because Slack (bafflingly) doesn't use real markdown, I've noticed some of my coworkers use asterisks for headers (like*Current*) so the header will actually be bold in the Slack UI. I don't like this, because it's not markdown headers, but I understand the need for it.

_{^{the real fix would be for Slack to implement markdown but I've given up hope on that}}

[evanthegrayt]

Closing this issue. While it would be nice, it really goes against my design pattern and would be a rather large change for not a lot of gain. If there's a lot of interest in this, maybe I'll reopen it.