kelp-v0.3.1 - The independent widget update

Hey developers,

as requested in #44, it should be optional to bind inventory widgets to specific players to be able to reuse them over the server runtime. This also has several design advantages as you do not have to specify the player multiple times, which would cause redundant code.

@Etrayed has therefore developed a solution that allows you to create global listeners for items and get the player instance only when you need it (when handling the click event). A detailed example of how the new global listener system can be applied, look at the /sweetinv command of the testing module that is shipped with this version.

You can read all changes and new features in this version's changelog.

Still, we would like to point out that Kelp is not yet in a production-ready stage. There have been no performance tests with big amounts of players nor the API code is final. All features are only available in Minecraft 1.8.8 now. Please be patient or report bugs and issues for further improvement.