Litematica

• Thread sleep / FIXER task reduction for allowing the thread to sleep. Placement toggles now fully unloads the chunks.
• Cap Max PM Threads to 2.
• Various optimizations to get the threads to sleep whenever there is no work.
• Add Main Rendering Toggle callback for clearing out the Placement Manager Chunks and stopping the Thread; (Or Restarting it)
• SchematicPlacement: Fix getSubRegionBoxes() not checking... the main placement enabled state. (@maruohon )
• fix: schematic placement toJson() if somehow we lost the origin point... (?)
• Add logic to ignore Water with Pick Block on a schematic; as requested by PearlescentMoon

NOTE: This release was in the oven for a long time to try to Beta test and tweak various PM Thread settings to reduce CPU usage. The CPU usage will still be a thing as long as the Thread has work; but it should go to sleep in less than a second after. Sleeping lasts 10 minutes max; and if it see's no tasks; it goes back to sleep.