Async logic framework, box2D dependencies

core/src/mindustry/async/AsyncProcess.java

@@ -0,0 +1,13 @@
+package mindustry.async;
+
+public interface AsyncProcess{
+
+    /** Synchronous. Called at the beginning of the main loop. */
+    void begin();
+
+    /** Async. Called in a separate thread. */
+    void process();
+
+    /** Sync. Called in the end of the main loop. */
+    void end();
+}