Links with undescore prefixed text are not handled correctly

[jubianchi]

Here is an exemple markup pointing to the bug :

http://api.skriv.io/convert/html?text=%3D+Links%0A%0A%3D%3D+Works%0A%0A%5B%5B_invoke+%7C+http%3A%2F%2Fwww.php.net%2Fmanual%2Ffr%2Flanguage.oop5.magic.php%23object.invoke%5D%5D%0A%5B%5B%23%23_invoke%23%23+%7C+http%3A%2F%2Fwww.php.net%2Fmanual%2Ffr%2Flanguage.oop5.magic.php%23object.invoke%5D%5D%0A%0A%3D%3D+Does+not+work%0A%0A%5B%5B__invoke+%7C+http%3A%2F%2Fwww.php.net%2Fmanual%2Ffr%2Flanguage.oop5.magic.php%23object.invoke%5D%5D%0A%5B%5B%23%23__invoke%23%23+%7C+http%3A%2F%2Fwww.php.net%2Fmanual%2Ffr%2Flanguage.oop5.magic.php%23object.invoke%5D%5D

[jubianchi]

as @marmotz told me we can bypass this by escaping underscore [[##\__invoke|http://...]] works

This is a duplicate of #3