Add ItemsStack interface, without any Inventory
Fixed javadoc, added missing @Overrides

I accidentally deleted this

I'm tired, I screwed up a few things

I'm tired, I screwed up a few things
Fixed Javadoc describing Order.BEFORE_POST and Order.POST to be cancelable. Fixes #98
Merge pull request #97 from zeuslightning125/master

Fixed existing javadoc, added missing @Overrides