This adds the feature to take a transaction that has no or very low fee
and telling the TransactionBuilder class to use a certain output to
pay needed fees from.
On the call to createTransaction money will be taken from the specified
output based on the specified fee-per-byte (default 1sat/byte).
As we moved most of the creation of a BufferPool to be via the
Streaming::pool() method, which uses a thread-local, it makes sense
to start cleaning up the design and make it more modern C++.
The above mentioned method would return a reference and you'd see
loads of places use `auto &pool =` which is less than ideal.
As the number of places where we actually instantiate a BufferPool
goes down, the usage of some sort of smart pointer makes more sense.
This now makes all APIs use BufferPool be wrapped in a shared_ptr.
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}
This adds support for the
Lexicographical Indexing of Transaction Inputs and Outputs
anonimize concepts of transactions directly in the transaction builder.
John Galt
tomFlowee