Fallout from the Flattenable change, update all its uses.
Additionnaly, fix/tighten size checks when (un)flatten()ing
things.
Removed the assumption by some flattenables (e.g.: Fence)
that the size passed to them would be exact (it can
and will be larger in some cases)
The code in Parcel is a bit complicated so that we don't
have to expose the full implementation (and also to
keep the code smallish).
Change-Id: I0bf1c8aca2a3128491b4f45510bc46667e566dde
e142428a9c