Raise of rule MD037 in correct situation

[rfresow]

The rule MD037 - Spaces inside emphasis markers is raised in the following correct situation:

New_value is old_value and new_value.

Using v0.44.4.

[DavidAnson]

You could escape the "_" characters to prevent this. It thinks they represent an embedded emphasis. While that wouldn't be possible in valid Markdown, this rule assumes it may be looking at invalid Markdown.

[DavidAnson]

Note to self: See also #408.