Related to https://github.com/monero-project/research-lab/issues/78
Added a relay rule that enforces the `unlock_time` field is equal to 0 for non-coinbase transactions.
UIs changed:
* Removed `locked_transfer` and `locked_sweep_all` commands from `monero-wallet-cli`
APIs changed:
* Removed `unlock_time` parameters from `wallet2` transfer methods
* Wallet RPC transfer endpoints send error codes when requested unlock time is not 0
* Removed `unlock_time` parameters from `construct_tx*` cryptonote core functions
- fix tx create from sources, input locking. Originally, creating a synthetic transactions with chaingen could create a transaction with outputs that are still locked in the current block, thus failing chain validation by the daemon. Simple unlock check was added. Some buggy tests were fixed as well as new unlock-checking version of tx creation rejected those, fixes are simple - mostly using correct block after a rewind to construct a transaction
When RingCT is enabled, outputs from coinbase transactions
are created as a single output, and stored as RingCT output,
with a fake mask. Their amount is not hidden on the blockchain
itself, but they are then able to be used as fake inputs in
a RingCT ring. Since the output amounts are hidden, their
"dustiness" is not an obstacle anymore to mixing, and this
makes the coinbase transactions a lot smaller, as well as
helping the TXO set to grow more slowly.
Also add a new "Null" type of rct signature, which decreases
the size required when no signatures are to be stored, as
in a coinbase tx.
