This clarifies the intent: the project is licenced under terms
of LGPL version 3 only, but the standard headers cover only "3 or later",
so we had to rewrite them.
In the same step, we removed author information from individual files
in favor of "SatoshiLabs and contributors", and include an AUTHORS
file that lists the contributors.
Apologies to those whose names are missing; please contact us if you wish
to add your info to the AUTHORS file.
This makes more sense, because bytes are immutable and callers have no business
mutating structures from the wire anyway.
Incidentally this should fix issue #236, where rlp library would treat
bytes and bytearrays differently and produce invalid structures in our usecase.
Also very minor nitpicks and code cleanup for neater typing.
