Refactor source layout

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

[no changelog]

src/main/kotlin/util/ScreenUtil.kt

@@ -0,0 +1,38 @@
+
+
+package moe.nea.firmament.util
+
+import net.fabricmc.fabric.api.client.event.lifecycle.v1.ClientTickEvents
+import net.minecraft.client.MinecraftClient
+import net.minecraft.client.gui.screen.Screen
+import moe.nea.firmament.Firmament
+
+object ScreenUtil {
+    init {
+        ClientTickEvents.START_CLIENT_TICK.register(::onTick)
+    }
+
+    private fun onTick(minecraft: MinecraftClient) {
+        if (nextOpenedGui != null) {
+            val p = minecraft.player
+            if (p?.currentScreenHandler != null) {
+                p.closeHandledScreen()
+            }
+            minecraft.setScreen(nextOpenedGui)
+            nextOpenedGui = null
+        }
+    }
+
+    private var nextOpenedGui: Screen? = null
+
+    fun setScreenLater(nextScreen: Screen?) {
+        val nog = nextOpenedGui
+        if (nog != null) {
+            Firmament.logger.warn("Setting screen ${if (nextScreen == null) "null" else nextScreen::class.qualifiedName} to be opened later, but ${nog::class.qualifiedName} is already queued.")
+            return
+        }
+        nextOpenedGui = nextScreen
+    }
+
+
+}