Words with (non-emphasis) underscores rejected

[Gabriella439]

Minimal reproducing example is a_b

A more realistic reproducing example is :fox_face:

[mrkkrp]

Yeah, this is a quirk of MMark. It is explained in the readme. You are supposed to espace the underscore with a backslash. Another annoying side-effect of this logic is that you cannot have e.g. emphasis that highlights only part of a word. Frankly, I'd need to change this, but I'm not sure when I will have time to do it.