====== spawnProjectile ======
  * Parameters and types:
    * shooter: numberSet the objid to which the thrown object belongs
    * itemid: numberthrowable id
    * x,y,z: numberstarting point of the thrown object
    * dstx, dsty, dstz: numberdestination of the thrown object
    * speed: numberThrowing speed
  * Return value and type:
     * code: numberSuccess (ErrorCode.OK) ErrorCode
     * objid: numberThe instance ID of the thrown object
  * The main function of this method is to generate projectiles
  * The specific use cases are as follows:

<code>
local code, objid = World:spawnProjectile(shooter, itemid, x, y, z, dstx, dsty, dstz, speed)
if code == ErrorCode.OK then
print('Execution success', code, objid )
else
print('Execution failed')
end
</code>