Adds the following command:
Whenever used, if you have a PLAYER_HEAD in your hand, it will be saved as an "itemDisplay" preset and it will also convert your item in hand (the player head) in a placer.

Adds PresetPlacer(s).
Placers hold in their NBT what type of preset they will place whenever right clicking/placing the Placer.
In order to remove a block created by a placer, just remove (left clicking/destroying) the block with any type of Placer (doesn't need to be the same Placer you used whenever you placed it).

Commands "itemdisplay" and "blockdisplay" now have the "placer" which allows getting a placer from a preset. This is the most intuitive way of placing and removing custom blocks (players without placers cannot remove/destroy blocks/presetBlocks)
An example: