Replace references to NEU with Firmament

src/main/java/moe/nea/firmament/mixins/MixinDownloadingTerrainScreen.java

@@ -0,0 +1,16 @@
+package moe.nea.firmament.mixins;
+
+import moe.nea.firmament.events.WorldReadyEvent;
+import net.minecraft.client.gui.screen.DownloadingTerrainScreen;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+
+@Mixin(DownloadingTerrainScreen.class)
+public class MixinDownloadingTerrainScreen {
+    @Inject(method = "close", at = @At("HEAD"))
+    public void onClose(CallbackInfo ci) {
+        WorldReadyEvent.Companion.publish(new WorldReadyEvent());
+    }
+}