Replace most checks for +o with oper:general

Replace most checks for +o with oper:general

I'm preparing to PR a succession of privs changes with the ultimate goal
of severely limiting the scope of the binary oper/user dichotomy and
move conceptually distinct oper functions into their own privs.

Accomplishing this is a non-trivial task, and can wait, but it's
inconvenient now to have such functions enabled by the same mechanism
that grants any privs at all--so I'm moving all of them to a
transitional priv with the intention of eroding that later.