stonecutter: improve backwards-compatibility

Builds targetting Minecraft versions below 1.21.6 will now once again contain the `getScreen` method with `Screen` as their return value instead of `MidnightConfigScreen`.
This ensures that mods compiled for older MidnightLib versions continue working as expected.

The return value has to be changed to `MidnightConfigScreen` in 1.21.6 and up due to NeoForge removing support for the `@OnlyIn` annotation – thus breaking server-only installations when referencing client-only classes like `Screen`.

gradle.properties

@@ -7,7 +7,7 @@ org.gradle.parallel=false
 #org.gradle.configureondemand=true
 
 # Mod properties
-mod.version=1.9.0-beta.1
+mod.version=1.9.0-beta.2
 mod.group=eu.midnightdust
 mod.id=midnightlib
 mod.name=MidnightLib

src/main/java/eu/midnightdust/lib/config/MidnightConfig.java

@@ -29,9 +29,17 @@ import java.util.function.Function;
 import java.util.function.Predicate;
 import java.util.regex.Pattern;
 
+//? if < 1.21.6 {
+/*//? fabric
+import net.fabricmc.api.*;
+//? neoforge
+/^import net.neoforged.api.distmarker.*;^/
+//? forge
+/^import net.minecraftforge.api.distmarker.*;^/
+*///?}
+
 /** MidnightConfig is an incredibly lightweight, but still fully-featured config library for Minecraft mods.<br>
  *  Originally based on <a href="https://github.com/Minenash/TinyConfig">TinyConfig</a> by Minenash.*/
-@SuppressWarnings("unchecked")
 public abstract class MidnightConfig {
     private static final Pattern INTEGER_ONLY = Pattern.compile("(-?[0-9]*)");
     private static final Pattern DECIMAL_ONLY = Pattern.compile("-?(\\d+\\.?\\d*|\\d*\\.?\\d+|\\.)");
@@ -67,6 +75,7 @@ public abstract class MidnightConfig {
      * */
     protected static <T extends MidnightConfig> T createInstance(String modid, Class<? extends MidnightConfig> configClass) {
         try {
+            //noinspection unchecked
             T instance = (T) configClass.getDeclaredConstructor().newInstance();
             instance.modid = modid;
             instance.configClass = configClass;
@@ -280,10 +289,16 @@ public abstract class MidnightConfig {
      * @param parent The parent screen, which will be returned to when exiting the config
      * @param modid The mod of which to load the config screen
      * */
+    //? if < 1.21.6 {
+    /*/^? fabric {^/ @Environment(EnvType.CLIENT) /^?} else {^/ /^@OnlyIn(Dist.CLIENT) ^//^?}^/
+    public static Screen getScreen(Screen parent, String modid) {
+    *///?} else {
     public static MidnightConfigScreen getScreen(Screen parent, String modid) {
+    //?}
         return configInstances.get(modid).getScreen(parent);
     }
 
+
     /**
      * Creates an instance of the config screen.
      * This can be overridden to return a fully custom config screen.