This will increase or decrease karma for the item.

If `config plugins.karma.allowUnaddressedKarma` is set to `True` (default since 2014.05.07), saying `boats++` will give 1 karma to `boats`, and `ships--` will subtract 1 karma from `ships`.

However, if you use this in a sentence, like `That deserves a ++. Kevin++`, 1 karma will be added to `That deserves a ++. Kevin`, so you should only add or subtract karma in a line that doesn't have anything else in it.

If `config plugins.karma.allowUnaddressedKarma` is set to `False`, you must address the bot with nick or prefix to add or subtract karma.
