Migration of old APIs and filenames to SCF namespace #150

As time evolves, SCF is likely to diverge from the ACF parent, and it should be considered how to adapt the existing codebase to a new namespace.

There is an initial attempt at adding a legacy mode in #92. However, we need to study the pros and cons of any action we take to divert from ACF, as the more the codebases diverge, the more challenging it is to backport security patches across both versions, which is in the interest of both user bases.