wrong italic and bold

[haennes]

Wrong in Editor Preview

*_this is italic and bold_*
*\_a*
this should not be bold or italic

is rendere as:
this is italic and bold
_a
this should not be bold or italic

This already works:

it does work this way around though:

*_this is italic and bold_*
_\*a_
this should not be bold or italic

Sadly I dont have any knowledge of vim script, so I won´t be able to make a PR fixing this :/