V2 - simplify modify methods

[dxinteractive]

Just pass parceldata in and out of these. Makes them much easier to deal with because there isn't some special case as the default.

• remove asRaw
• create a prepareUpdater(updater) function that will merge returned parcel data onto existing, and returned meta items onto existing. Perhaps it can also accept multiple updaters and therefore be a pipe.
• change codebase to suit, including all self usages