Eliminate ALL cascading worldgen lag, with the following changes:

- Offset structures by minus half their width in x/z (as well as the usual +8), so they can't ever spill out of the 2x2 chunk area being generated (provided they are less than 16 blocks wide, which mine are)
- Pass the block placement flags 16 | 2 to Template#addBlocksToWorld instead of just 2, to prevent neighbour updates
- Ignore unloaded blocks when removing floating trees (in theory there can't be trees there anyway)

src/main/java/electroblob/wizardry/worldgen/WorldGenObelisk.java

@@ -62,7 +62,7 @@ public class WorldGenObelisk extends WorldGenSurfaceStructure {
 		ITemplateProcessor processor = (w, p, i) -> i.blockState.getBlock() instanceof BlockRunestone ? new Template.BlockInfo(
 				i.pos, i.blockState.withProperty(BlockRunestone.ELEMENT, element), i.tileentityData) : i;
 
-		template.addBlocksToWorld(world, origin, processor, settings, 2);
+		template.addBlocksToWorld(world, origin, processor, settings, 2 | 16);
 
 		WizardryAntiqueAtlasIntegration.markObelisk(world, origin.getX(), origin.getZ());