Direct all BlockPlaceEvents to a singular location. Fixes BUKKIT-3438

By having a single function to process BlockPlacement logic, we make
it so that there is consistent behavior throughout all BlockPlace
events. This should allow for easier troubleshooting and less diffs
in source.

This also fixes BUKKIT-3463 by including the correct coordinates that
were clicked to the event.
Call BlockPlaceEvent for skulls the same as other blocks. BUKKIT-3406

When the skull BlockPlaceEvent was added it was made so the event
would be called after all the data has been set, however this is a
behavior change that is inconsistent with other BlockPlaceEvents.
Instead, if people wish to get the block data they should schedule
a task.

Relates to: BUKKIT-3438
Fix metadata loss in modded block placement event from BUKKIT-3438 fix

Allow all metadata to be placed in ItemBlock, instead of 0. Required
to allow placing mod blocks with metadata after fix introduced for:
Direct all BlockPlaceEvents to a singular location. Fixes BUKKIT-3438