The IDE include checker got to the point where it is actually useful and
this removes a lot of unneeded includes.
Naturally, especially for headers like util.h, this may mean we need to
re-add includes in consuming cpp files that bloats the diff a bit.
This removes the transaction-signing code from the hub internal codebase.
The only user for this was the API call signrawtransaction,
and a lot of unit testing code.
I'd argue that if the user needs to send a private key to the hub via
RPC for signing his transaction, then they are doing it wrong.
This also removes the duplicate test double_spend which tests
functionality also tested in the DoubleSpendProofTest.
As an aside, the flowee/utils library still has full signing capability
and we suggest using the TransactionBuilder API for that.
This follows the coding style guideline that the file that contains a
class should follow the exact name of this (main) class.
key.{h|cpp} -> PrivateKey.{h|cpp}
tomFlowee
TomZ