This reverts PR #4906, "Coinselection prunes extraneous inputs from
ApproximateBestSubset".
Apparently the previous behavior of slightly over-estimating the set of
inputs was useful in cleaning up UTXOs.
See also #7664, #7657, as well as 2016-07-01 discussion on #bitcoin-core-dev IRC.
Verify that results correct (match known values), consistent (encrypt->decrypt
matches the original), and compatible with the previous openssl implementation.
Also check that failed encrypts/decrypts fail the exact same way as openssl.
* Introduce new constant MIN_CHANGE and use it instead of the
hardcoded "CENT"
* Add test case for MIN_CHANGE
* Introduce new constant for -mintxfee default:
DEFAULT_TRANSACTION_MINFEE = 1000