Refactored the configuration layer, and expose a 'configure' command

not easy because a compat lib should not only provide the interface, but also hook into the json serialization to make it work properly for implementations of the interface => no userland implementation.
And for a pecl implementation, it might already exist. I haven't checked whether jsonc can be installed on 5.3 and whether it would provide these new features on 5.3 or no.