Add common pathing code and SimplePathing module

src/main/java/com/replaymod/pathing/change/RemovePath.java

@@ -0,0 +1,50 @@
+package com.replaymod.pathing.change;
+
+import com.google.common.base.Preconditions;
+import com.replaymod.pathing.path.Path;
+import com.replaymod.pathing.path.Timeline;
+import lombok.NonNull;
+
+/**
+ * Adds a new property.
+ */
+public final class RemovePath implements Change {
+    @NonNull
+    public static RemovePath create(Path path) {
+        return new RemovePath(path.getTimeline().getPaths().indexOf(path));
+    }
+
+    RemovePath(int path) {
+        this.path = path;
+    }
+
+    /**
+     * Path index
+     */
+    private final int path;
+
+    /**
+     * The removed path
+     */
+    private volatile Path oldPath;
+
+    private boolean applied;
+
+    @Override
+    public void apply(Timeline timeline) {
+        Preconditions.checkState(!applied, "Already applied!");
+
+        oldPath = timeline.getPaths().remove(path);
+
+        applied = true;
+    }
+
+    @Override
+    public void undo(Timeline timeline) {
+        Preconditions.checkState(applied, "Not yet applied!");
+
+        timeline.getPaths().add(path, oldPath);
+
+        applied = false;
+    }
+}