rc is still a type, but a more complicated one

theories/lifetime/frac_borrow.v

theories/lifetime/lifetime.v

theories/lifetime/lifetime_sig.v

theories/lifetime/model/accessors.v

theories/lifetime/model/reborrow.v

theories/typing/borrow.v

theories/typing/lib/rc.v

theories/typing/lib/refcell/refcell.v

theories/typing/lib/rwlock/rwlock.v

theories/typing/type_sum.v

theories/typing/util.v