Pass arguments to the parent constructor

In the Animal-Cat example ( Baboosh/doc/man.rst )
When we create a Cat Object

new Cat tom "Tom"

We get "$1: unbound variable" error at parent constructor.

This is because the $_init_args is not being passed to the parent constructor.

This is a small fix. 

I really admire and appreciate the efforts of metal3d for the simple and efficient framework https://github.com/metal3d/Baboosh/