For some reason, I didn't figure out that it's completely possible having more than a single World during runtime.
From now on, each World will hold PresetBlocks for itself.
Not just that, I fixed an issue in which when a Chunk that held PresetBlocks unloaded, and was later loaded again, it loaded just without the PresetBlocks (you would only see the invisible blocks / barriers)

Localization is still not done

Changes since v1.2.3

• e59c51f Loads PresetBlocks again if Chunk was reloaded
• c0df0ce Splits PresetBlockAssetDirector into worlds
• c7a1fb9 Refactored blockasset to presetblock
• a21f5ee Uses BlobLib's DisplayOperator, Adds DesignDisplayOperator (for future usage), Adds DesignDisplayOperatorReader, PresetBlockAsset correctly returns its DisplayElementType

Plugin is now compatible with BlobLib 1.697.6
Localization is still not done

Adds updater

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: