Properly link flecs library

engine/libs/flecs/templates/cpp/flecs/src/main.cpp

@@ -0,0 +1,13 @@
+#include <${id underscore}.h>
+#include <iostream>
+
+int main(int argc, char *argv[]) {
+    flecs::world world(argc, argv);
+
+    world.set_target_fps(1);
+
+    std::cout << "Application ${id} is running, press CTRL-C to exit..." << std::endl;
+
+    /* Run systems */
+    while (world.progress()) { }
+}