Fixed markdown link parsing

Reddit allows markdown links to have a space between the [] and () tags. These links are not parsed correctly by Diode. Here is an [example comment](http://www.reddit.com/r/pics/comments/1z5xbz/fishing/cfr7eso) demonstrating this issue. I have not tested this change, and I am not sure if I did the regex correctly as I Java regex's seem to be slightly different from Perl 5's.