Spongeapi: Expose the click position for placing a block

[gabizou]

In 1.9, it's pretty evident that the client is correctly sending a block placement packet with a correct interaction point and for some plugins, this might come of use. Currently however, the vanilla source doesn't seem to use the exact coordinates in any way (alluding to the possibility that they're simply adding it for the modding platforms).

I understand that this would likely have to be done through some sort of changes in the InteractBlockEvent where it's from players specifically as entities are not likely to include such information when interacting against blocks.

[gabizou]

I'm an idiot. I didn't see that the interaction points were already included in InteractEvent.