add dummy function with todo

packages/core/splitLanes.mjs

@@ -0,0 +1,8 @@
+function splitLanes(haps) {
+  // TODO: split haps into multiple arrays so that no overlapping events are in the same array
+  // also make sure the lanes are packed as tight as possible
+  // use logic analogous to drawLine
+  return [haps];
+}
+
+export default splitLanes;