Refactor source layout

Introduce compat source sets and move all kotlin sources to the main directory

[no changelog]

src/main/kotlin/events/ParticleSpawnEvent.kt

@@ -0,0 +1,18 @@
+
+
+package moe.nea.firmament.events
+
+import org.joml.Vector3f
+import net.minecraft.particle.ParticleEffect
+import net.minecraft.util.math.Vec3d
+
+data class ParticleSpawnEvent(
+    val particleEffect: ParticleEffect,
+    val position: Vec3d,
+    val offset: Vector3f,
+    val longDistance: Boolean,
+    val count: Int,
+    val speed: Float,
+) : FirmamentEvent.Cancellable() {
+    companion object : FirmamentEventBus<ParticleSpawnEvent>()
+}