When member joins the group and needs to receive an SST it won't
receive the corresponding menbership view event because the SST
happens after the event and will already include the effects of
all events ordered before it. The view then must be recovered from
the received state.
Minor renames and cleanups.
References codership/wsrep-lib#18
it on disconnect.
- Don't rely on own index from the view because the view may come from
another member (IST/SST), instead always determine own index from own ID.
Refs codership/wsrep-lib#13
