Avoid accidental escaped bullet points

[jlevy]

It's common to see bullet points that are a little off get reflow/remarked as literal dashes. For example something like

- Blah blah blah blah blah blah.
 - Blah blah.

turns into

- Blah blah blah blah blah blah.
  \- Blah blah.

We should figure out a way to make this less common and annoying. It's very rare to have a sentence begin with a literal dash.