For ordered lists the prefix recognized any [a-z]+ string. That caused an issue if a line started with a [a-z]+ string followed by a dot, if that string was not a single letter or a valid roman numeral. That would dedent the line in the editor pane as if the string was a prefix.
This changes the regular expression to recognize as prefix only:
- one or more digits
- or a single lower case letter
- or a valid roman numeral in lower case letters