Cooperative End Access

Fixed some bugs:

• Don't give back an Eye of Ender on removal in Creative mode.
• Don't swallow the Eye of Ender on successful removal with a full inventory (shouldn't happen I think since you need an open hand?). But just to be safe.
• Open all collapsed but otherwise complete portals when the dragon dies.
• Breaking an End Frame now removes its owner from tracking.
• Placing an Eye of Ender into an End Frame in an invalid End Portal structure now does not throw an error in the server logs.

Might've introduced new ones, let's see what happens.

Full Changelog: https://github.com/ganyuke/CooperativeEndAccess/compare/v0.1.1...v0.1.2