Modify SendCommandEvent

[Yeregorix]

Currently SendCommandEvent#getResult() always returns an empty CommandResult since the event is thrown before the command is executed. The method is almost useless. I propose to split SendCommandEvent in SendCommandEvent.Pre and SendCommandEvent.Post and move the current method to SendCommandEvent.Pre#getResult()

[ryantheleach]

Related: #1333

Note that there is a usecase for having getResult on the pre-event, it's the result in the case that the event is cancelled currently.

As noted on that PR I don't know if this is behaviour we should be keeping, or if it's an intentional design feature, that can't be replicated any other way.

[ImMorpheus]

Fixed by 7dd9f3f

(the name is slightly different: ExecuteCommandEvent.Pre and ExecuteCommandEvent.Post)