Support MM1 in addition to MM2 (fixes #162)

Cause the latest OptiFabric on 1.14.4 still ships that and it has no support for
entrypoints.

src/main/java/com/replaymod/core/ReplayModMMLauncher.java

@@ -12,8 +12,18 @@ import java.util.Optional;
 // We need to wait for MM to call us, otherwise we might initialize our mixins before it calls optifabric which would
 // result in OF classes not existing while our mixins get resolved.
 public class ReplayModMMLauncher implements Runnable {
+    private static boolean ran;
+
     @Override
     public void run() {
+        // If this is MM2, then we're currently getting called because of our entrypoint declaration.
+        // For backwards compatibility with MM1, we also declare our early_riser via custom metadata and MM2 supports
+        // that as well and will therefore call us twice.
+        if (ran) {
+            return;
+        }
+        ran = true;
+
         Mixins.addConfiguration("mixins.compat.mapwriter.replaymod.json");
         Mixins.addConfiguration("mixins.compat.shaders.replaymod.json");
         Mixins.addConfiguration("mixins.core.replaymod.json");