scasp_common:split

Given a predicate functor, return the components. Since the arity is at the end, we have to be creative to remove it.

Arguments:

`Functor`	- The predicate functor, of the form Name_Arity.
`Name`	- The name with the arity stripped. A list of characters.
`Arity`	- The arity of the predicate, or -1 if no arity is attached.