Intraword italics not using Markdown spec

[mlncstr]

Right now, intraword italics are using underscores instead of single *.

According to Github Flavored Markdown Spec

Many implementations have also restricted intraword emphasis to the * forms, to avoid unwanted emphasis in words containing internal underscores. (It is best practice to put these in code spans, but users often do not.)

internal emphasis: foobarbaz no emphasis: foo_bar_baz

[domchristie]

Well spotted! We'll probably need a fix for this, but in the meantime you may want to set the emDelimiter option to *, which I think should fix it.

[mlncstr]

Thanks @domchristie will try out the delimiter to see if that works for us