Problems with emphasis inside words.

[arodland]

There seem to be a number of problems when emphasis markers (* or ** or _ or __) occur inside of words. Specific examples:

• "a*b*" should produce "a<em>b</em>" but instead produces "a*b*".
• "a**b**" should produce "a<strong>b</strong>" but instead produces "a*<em>b</em>*".
• However: "*b*a" and "**b**a" behave as expected.

Underscores appear to be broken in the same ways (and correct in the same ways) as asterisks.