Adds a new entity to scene with an initial position and scales it using scale.
This function returns the new entity ID.
// full sized crate
AddScaledEntity("crate.ent", vector3(200,200,0), 1.0f);
// half sized crate
AddScaledEntity("crate.ent", vector3(200,300,0), 0.5f);
// double sized crate
AddScaledEntity("crate.ent", vector3(200,400,0), 2.0f);