Fixed many missing event-calls

[supercrafter333]

No description provided.

[supercrafter333]

This doesn't fix the bug that the PlotClaimAsyncEvent isn't called!

[supercrafter333]

I'll need help to fix that bug.

[supercrafter333]

libAsyncEvent #2 should be fixed before merging this.

[ColinHDev]

Since these events' listener execution is asynchronous, the return of their call() method does not automatically indicate that all listeners already finished executing. Instead, we rely on a callback, that notifies the plugin once every listener successfully handles the event and we can continue with the current logic.
The create() method only hides this and wraps it around a generator, so we can easily use it in combination with await-generator, for example here in the PlotMergeAsyncEvent.