Support for unified diff

[trombonehero]

I don't see an option for unified diff formatting on http://prismjs.com/download.html... this would be a very handy language to implement. It seems like this might be a pretty easy change? I don't know the Prism API well, but I suspect that half of the change would look like:

Prism.languages.diff = {
    'addition': /+.*/,
    'deletion': /-.*/
}

but I'm not sure how to turn 'addition' and 'deletion' into appropriate class names... these aren't normal keywords, comments, etc. Does the Prism CSS have classes for things like addition and deletion?

[Golmote]

Hi, thanks for reporting. It should be fixed now. Just use the git component for diffs.

Note that there is also a pending PR (#450) to make a proper component for diffs. It might be merged some day.