BlockPlacedEvent

Added BlockPlacedEvent. Still need to implement it.
Revert "BlockPlacedEvent"

This reverts commit 52b71b8c2a2c68d3360e1b3e87a5a640ad962610.
Revert "Revert "BlockPlacedEvent""

This reverts commit 2d4862738228d0b499a0dba4d2a9225d9bc7aadf.