Fix texture select functions not showing up

in engine prototype

src/Engines/Extensions/index.ts

@@ -12,4 +12,7 @@ export * from "./engine.renderTargetCube";
 export * from "./engine.webVR";
 export * from "./engine.uniformBuffer";
 export * from "./engine.views";
+
+// must import first since nothing references the exports
+import "./engine.textureSelector";
 export * from "./engine.textureSelector";